109 KiB
Overview
The HttpApi modules let you describe your HTTP API once and use that description to run a server, generate documentation, and create a type-safe client.
An API is built from three building blocks:
- HttpEndpoint — a single route (path + HTTP method) with schemas for its request and response.
- HttpApiGroup — a collection of related endpoints (e.g., all user-related routes).
- HttpApi — the top-level object that combines groups into a complete API.
HttpApi
├── HttpGroup
│ ├── HttpEndpoint
│ └── HttpEndpoint
└── HttpGroup
├── HttpEndpoint
├── HttpEndpoint
└── HttpEndpoint
From one API definition you can:
- Start a server that implements and serves every endpoint.
- Generate documentation (Scalar or Swagger) automatically.
- Derive a client with a typed method for each endpoint.
One definition powers the server, docs, and client — change it once and everything stays in sync.
Getting Started
Defining and Implementing an API
Let's build a minimal API with one endpoint that returns "Hello, World!". You'll define what the endpoint looks like, implement it, and start a server.
HttpApi ("MyApi")
└── HttpGroup ("Greetings")
└── HttpEndpoint ("hello-world")
Example (Hello World)
import { NodeHttpServer, NodeRuntime } from "@effect/platform-node"
import { Effect, Layer, Schema } from "effect"
import { HttpRouter } from "effect/http"
import { HttpApi, HttpApiBuilder, HttpApiEndpoint, HttpApiGroup } from "effect/http-api"
import { createServer } from "node:http"
// Definition
const Api = HttpApi.make("MyApi").add(
// Define the API group
HttpApiGroup.make("Greetings").add(
// Define the endpoint
HttpApiEndpoint.get("hello", "/", {
// Define the success schema
success: Schema.String
})
)
)
// Implementation
const GroupLayer = HttpApiBuilder.group(
Api,
"Greetings", // The name of the group to handle
(handlers) =>
handlers.handle(
"hello", // The name of the endpoint to handle
() => Effect.succeed("Hello, World!") // The handler function
)
)
// Server
const ApiLayer = HttpApiBuilder.layer(Api).pipe(
Layer.provide(GroupLayer),
HttpRouter.serve,
Layer.provide(NodeHttpServer.layer(createServer, { port: 3000 }))
)
// Launch
Layer.launch(ApiLayer).pipe(NodeRuntime.runMain)
After running the code, open a browser and navigate to http://localhost:3000. The server will respond with:
Hello, World!
Serving The Auto Generated OpenAPI Documentation
Adding a documentation layer gives you an interactive page where you (and your API consumers) can explore endpoints, try requests, and see response shapes — all generated automatically from your API definition. You can choose between the HttpApiScalar module (Scalar UI) or the HttpApiSwagger module (Swagger UI); both do the same job.
Example (Serving Scalar Documentation)
To include Scalar in your server setup, provide the HttpApiScalar.layer when configuring the server.
const ApiLayer = HttpApiBuilder.layer(Api).pipe(
// Provide the Scalar layer so clients can access auto-generated docs
Layer.provide(GroupLayer),
Layer.provide(HttpApiScalar.layer(Api)),
HttpRouter.serve,
Layer.provide(NodeHttpServer.layer(createServer, { port: 3000 }))
)
After running the server, open your browser and navigate to http://localhost:3000/docs.
This URL will display the Scalar documentation, allowing you to explore the API's endpoints, request parameters, and response structures interactively.
Example (Serving Swagger Documentation)
To include Swagger in your server setup, provide the HttpApiSwagger.layer when configuring the server.
const ApiLayer = HttpApiBuilder.layer(Api).pipe(
Layer.provide(GroupLayer),
// Provide the Swagger layer so clients can access auto-generated docs
Layer.provide(HttpApiSwagger.layer(Api)), // "/docs" is the default path.
// or Layer.provide(HttpApiScalar.layer(Api)),
HttpRouter.serve,
Layer.provide(NodeHttpServer.layer(createServer, { port: 3000 }))
)
After running the server, open your browser and navigate to http://localhost:3000/docs.
This URL will display the Swagger documentation, allowing you to explore the API's endpoints, request parameters, and response structures interactively.
Adding Annotations to Schemas
Annotations attach extra information to your schemas — like a human-readable description or an identifier shown in the docs UI. They don't change runtime behavior; they enrich the generated documentation.
const User = Schema.Struct({
id: Schema.Int,
name: Schema.String
}).annotate({
description: "A user", // The description of the user
identifier: "User" // Used in the Scalar UI under the Model section
})
Deriving a Client
Once you've defined an API, you can generate a fully typed client from it using the HttpApiClient module. The client gives you a method for every endpoint, so calling your API feels like calling a local function — with full type safety and no manual HTTP handling.
Example (Deriving and Using a Client)
import { NodeHttpServer, NodeRuntime } from "@effect/platform-node"
import { Effect, Layer, Schema } from "effect"
import { HttpRouter } from "effect/http"
import { FetchHttpClient } from "effect/http"
import { HttpApi, HttpApiBuilder, HttpApiClient, HttpApiEndpoint, HttpApiGroup } from "effect/http-api"
import { createServer } from "node:http"
const Api = HttpApi.make("MyApi")
.add(
HttpApiGroup.make("Greetings")
.add(
HttpApiEndpoint.get("hello", "/", {
success: Schema.String
})
)
)
const GroupLayer = HttpApiBuilder.group(
Api,
"Greetings",
(handlers) => handlers.handle("hello", () => Effect.succeed("Hello, World!"))
)
const ApiLayer = HttpApiBuilder.layer(Api).pipe(
Layer.provide(GroupLayer),
HttpRouter.serve,
Layer.provide(NodeHttpServer.layer(createServer, { port: 3000 }))
)
Layer.launch(ApiLayer).pipe(NodeRuntime.runMain)
// Create a program that derives and uses the client
const program = Effect.gen(function*() {
// Derive the client
const client = yield* HttpApiClient.make(Api, {
baseUrl: "http://localhost:3000"
})
// Call the "hello-world" endpoint
const hello = yield* client.Greetings.hello()
console.log(hello)
})
// Provide a Fetch-based HTTP client and run the program
Effect.runFork(program.pipe(Effect.provide(FetchHttpClient.layer)))
/*
Output:
[18:55:26.051] INFO (#2): Listening on http://0.0.0.0:3000
[18:55:26.057] INFO (#12) http.span=2ms: Sent HTTP response { 'http.method': 'GET', 'http.url': '/', 'http.status': 200 }
Hello, World!
*/
Design Principles
- Schemas first: Every piece of data flowing in or out of an endpoint — path params, query strings, headers, payloads, responses, and errors — is described by a schema. The framework uses these schemas to validate requests, serialize responses, generate docs, and type the client.
- Metadata lives on schemas: Configuration like HTTP status codes and content types is attached directly to the schema via annotations, not to the endpoint. This keeps all the information about a data shape in one place.
In particular:
- Request
- Payload encoding / content type is controlled with
HttpApiSchema.as*helpers:asJson— parse the body as JSON (default)asFormUrlEncoded— parse the body as URL-encoded form dataasText— parse the body as plain textasUint8Array— parse the body as raw binary dataasMultipart— parse the body as a multipart form (for file uploads)asMultipartStream— parse the body as a streaming multipart form
- Payload encoding / content type is controlled with
- Response
- Status code is set via the
HttpApiSchema.statusAPI (orhttpApiStatusannotation) - Encoding / content type is controlled with
HttpApiSchema.as*helpers:asJson— send the body as JSON (default)asFormUrlEncoded— send the body as URL-encoded form dataasText— send the body as plain textasUint8Array— send the body as raw binary data
- Status code is set via the
Anatomy of an Endpoint
An endpoint definition describes everything the framework needs to know about a single HTTP route: which URL parameters it expects, what query strings and headers it reads, what the request body looks like, and what it can respond with (both successes and errors). All of these are optional.
HttpApiEndpoint automatically coerces request and response schemas by default. Path / query / header schemas use Schema.toCodecStringTree, while JSON payload / success / error schemas use Schema.toCodecJson. This means you can define schemas in their natural domain types (for example Schema.Int), without manually adding string / JSON transformations.
const User = Schema.Struct({
id: Schema.String,
name: Schema.String
})
// ┌─── Endpoint name (used in the client as the method name)
// │ ┌─── Endpoint path
// ▼ ▼
HttpApiEndpoint.patch("updateUser", "/user/:id", {
// Parameters from the route pattern (e.g. /user/:id).
// Can be a record of fields or a full schema.
params: {
// ┌─── Schema for the "id" parameter.
// ▼
id: Schema.String
},
// (optional) Query string parameters (e.g. ?mode=merge).
// Can be a record of fields or a full schema.
query: {
// ┌─── Schema for the "mode" query parameter
// ▼
mode: Schema.Literals(["merge", "replace"])
},
// (optional) Request headers.
// Can be a record of fields or a full schema.
headers: {
"x-api-key": Schema.String,
"x-request-id": Schema.String
},
// The request payload can be a single schema or an array of schemas.
// - Default encoding is JSON.
// - Default status for success is 200.
// For GET requests, the payload must be a record of schemas.
payload: [
// JSON payload (default encoding).
Schema.Struct({
name: Schema.String
}),
// text/plain payload.
Schema.String.pipe(HttpApiSchema.asText())
],
// Possible success responses.
// Default is 200 OK with no content if omitted.
success: [
// JSON response (default encoding).
User,
// text/plain response with a custom status code.
Schema.String
.pipe(
HttpApiSchema.status(206),
HttpApiSchema.asText()
)
],
// Possible error responses.
error: [
// Default is 500 Internal Server Error with JSON encoding.
Schema.Finite,
// text/plain error with a custom status code.
Schema.String
.pipe(
HttpApiSchema.status(404),
HttpApiSchema.asText()
),
// Any schema that encodes to `Schema.Void` is treated as "no content".
// Here it uses a custom status code.
Schema.Void
.pipe(HttpApiSchema.status(401))
]
})
Routing
This section walks through defining endpoints for common HTTP methods — GET, POST, DELETE, and PATCH — using a user-management API as a running example:
GET /users— retrieve all users.GET /users/:userId— retrieve a specific user by ID.POST /users— create a new user.DELETE /users/:userId— delete a user by ID.PATCH /users/:userId— update a user by ID.
GET
Use HttpApiEndpoint.get to create a GET endpoint. Provide a name (used as the method name in generated clients), a path, and optionally a success schema describing what the endpoint returns. Without a success schema the default response is 204 No Content.
Example (Defining a GET Endpoint to Retrieve All Users)
import { NodeHttpServer, NodeRuntime } from "@effect/platform-node"
import { Effect, Layer, Schema } from "effect"
import { HttpRouter } from "effect/http"
import { HttpApi, HttpApiBuilder, HttpApiEndpoint, HttpApiGroup, HttpApiScalar } from "effect/http-api"
import { createServer } from "node:http"
// Define a schema representing a User entity
const User = Schema.Struct({
id: Schema.Int,
name: Schema.String
})
const Api = HttpApi.make("MyApi")
.add(
HttpApiGroup.make("Users")
.add(
// Define the "getUsers" endpoint, returning a list of users
// ┌─── Endpoint name (used in the client as the method name)
// │ ┌─── Endpoint path
// ▼ ▼
HttpApiEndpoint.get("getUsers", "/users", {
// ┌─── success schema
// │
// ▼
success: Schema.Array(User)
})
)
)
const GroupLayer = HttpApiBuilder.group(
Api,
"Users",
(handlers) =>
handlers.handle("getUsers", () =>
Effect.succeed(
[{ id: 1, name: "User 1" }, { id: 2, name: "User 2" }]
))
)
const ApiLayer = HttpApiBuilder.layer(Api).pipe(
Layer.provide(GroupLayer),
Layer.provide(HttpApiScalar.layer(Api)),
HttpRouter.serve,
Layer.provide(NodeHttpServer.layer(createServer, { port: 3000 }))
)
Layer.launch(ApiLayer).pipe(NodeRuntime.runMain)
POST
Use HttpApiEndpoint.post to create an endpoint that accepts data. The payload option describes the shape of the request body, and success describes what the endpoint returns.
When a group has more than one endpoint, use .handleAll to register all the handlers in a single call, keyed by endpoint name. Single endpoints can still be registered one at a time with .handle.
Example (Defining a POST Endpoint with Payload and Success Schemas)
import { NodeHttpServer, NodeRuntime } from "@effect/platform-node"
import { Effect, Layer, Schema } from "effect"
import { HttpRouter } from "effect/http"
import { HttpApi, HttpApiBuilder, HttpApiEndpoint, HttpApiGroup, HttpApiScalar } from "effect/http-api"
import { createServer } from "node:http"
const User = Schema.Struct({
id: Schema.Int,
name: Schema.String
})
const Api = HttpApi.make("MyApi")
.add(
HttpApiGroup.make("Users")
.add(
HttpApiEndpoint.get("getUsers", "/users", {
success: Schema.Array(User)
}),
HttpApiEndpoint.get("getUser", "/user/:id", {
params: {
id: Schema.Int
},
success: User
}),
// Define a POST endpoint for creating a new user
HttpApiEndpoint.post("createUser", "/user", {
// Define the request body schema (payload)
payload: User,
// Define the schema for a successful response
success: User
})
)
)
const GroupLayer = HttpApiBuilder.group(
Api,
"Users",
(handlers) =>
handlers.handleAll({
getUsers: () =>
Effect.succeed(
[{ id: 1, name: "User 1" }, { id: 2, name: "User 2" }]
),
getUser: (ctx) => {
const id = ctx.params.id
return Effect.succeed({ id, name: `User ${id}` })
},
createUser: (ctx) => {
// ┌─── User
// ▼
const user = ctx.payload
return Effect.succeed(user)
}
})
)
const ApiLayer = HttpApiBuilder.layer(Api).pipe(
Layer.provide(GroupLayer),
Layer.provide(HttpApiScalar.layer(Api)),
HttpRouter.serve,
Layer.provide(NodeHttpServer.layer(createServer, { port: 3000 }))
)
Layer.launch(ApiLayer).pipe(NodeRuntime.runMain)
DELETE
Use HttpApiEndpoint.delete to create an endpoint that removes a resource.
Example (Defining a DELETE Endpoint with Parameters)
import { NodeHttpServer, NodeRuntime } from "@effect/platform-node"
import { Effect, Layer, Schema } from "effect"
import { HttpRouter } from "effect/http"
import { HttpApi, HttpApiBuilder, HttpApiEndpoint, HttpApiGroup, HttpApiScalar } from "effect/http-api"
import { createServer } from "node:http"
const User = Schema.Struct({
id: Schema.Int,
name: Schema.String
})
const IdParam = Schema.Int
const Api = HttpApi.make("MyApi")
.add(
HttpApiGroup.make("Users")
.add(
HttpApiEndpoint.get("getUsers", "/users", {
success: Schema.Array(User)
}),
HttpApiEndpoint.get("getUser", "/user/:id", {
params: {
id: IdParam
},
success: User
}),
HttpApiEndpoint.post("createUser", "/user", {
payload: User,
success: User
}),
HttpApiEndpoint.delete("deleteUser", "/user/:id", {
params: {
id: IdParam
}
})
)
)
const GroupLayer = HttpApiBuilder.group(
Api,
"Users",
(handlers) =>
handlers.handleAll({
getUsers: () =>
Effect.succeed(
[{ id: 1, name: "User 1" }, { id: 2, name: "User 2" }]
),
getUser: (ctx) => {
const id = ctx.params.id
return Effect.succeed({ id, name: `User ${id}` })
},
createUser: (ctx) => {
const user = ctx.payload
return Effect.succeed(user)
},
deleteUser: (ctx) => {
const id = ctx.params.id
return Effect.log(`Deleting user ${id}`)
}
})
)
const ApiLayer = HttpApiBuilder.layer(Api).pipe(
Layer.provide(GroupLayer),
Layer.provide(HttpApiScalar.layer(Api)),
HttpRouter.serve,
Layer.provide(NodeHttpServer.layer(createServer, { port: 3000 }))
)
Layer.launch(ApiLayer).pipe(NodeRuntime.runMain)
PATCH
Use HttpApiEndpoint.patch to create an endpoint that partially updates a resource. Like POST, you can define payload (the fields to update) and success (the response after the update).
Example (Defining a PATCH Endpoint for Updating a User)
import { NodeHttpServer, NodeRuntime } from "@effect/platform-node"
import { Effect, Layer, Schema } from "effect"
import { HttpRouter } from "effect/http"
import { HttpApi, HttpApiBuilder, HttpApiEndpoint, HttpApiGroup, HttpApiScalar } from "effect/http-api"
import { createServer } from "node:http"
const User = Schema.Struct({
id: Schema.Int,
name: Schema.String
})
const IdParam = Schema.Int
const Api = HttpApi.make("MyApi")
.add(
HttpApiGroup.make("Users")
.add(
HttpApiEndpoint.get("getUsers", "/users", {
success: Schema.Array(User)
}),
HttpApiEndpoint.get("getUser", "/user/:id", {
params: {
id: IdParam
},
success: User
}),
HttpApiEndpoint.post("createUser", "/user", {
payload: User,
success: User
}),
HttpApiEndpoint.delete("deleteUser", "/user/:id", {
params: {
id: IdParam
}
}),
HttpApiEndpoint.patch("updateUser", "/user/:id", {
params: {
id: IdParam
},
// Specify the schema for the request payload
payload: Schema.Struct({
name: Schema.String // Only the name can be updated
}),
// Specify the schema for a successful response
success: User
})
)
)
const GroupLayer = HttpApiBuilder.group(
Api,
"Users",
(handlers) =>
handlers.handleAll({
getUsers: () =>
Effect.succeed(
[{ id: 1, name: "User 1" }, { id: 2, name: "User 2" }]
),
getUser: (ctx) => {
const id = ctx.params.id
return Effect.succeed({ id, name: `User ${id}` })
},
createUser: (ctx) => {
const user = ctx.payload
return Effect.succeed(user)
},
deleteUser: (ctx) => {
const id = ctx.params.id
return Effect.log(`Deleting user ${id}`)
},
updateUser: (ctx) => {
const id = ctx.params.id
return Effect.succeed({ id, name: `User ${id}` })
}
})
)
const ApiLayer = HttpApiBuilder.layer(Api).pipe(
Layer.provide(GroupLayer),
Layer.provide(HttpApiScalar.layer(Api)),
HttpRouter.serve,
Layer.provide(NodeHttpServer.layer(createServer, { port: 3000 }))
)
Layer.launch(ApiLayer).pipe(NodeRuntime.runMain)
Parameters
Path parameters let you capture dynamic values from the URL. For example, /user/:id extracts the id segment. Use the params option to declare a record of fields or a full schema — the framework will parse and validate the value before your handler runs.
Example (Defining a GET Endpoint to Retrieve a User by ID)
import { NodeHttpServer, NodeRuntime } from "@effect/platform-node"
import { Effect, Layer, Schema } from "effect"
import { HttpRouter } from "effect/http"
import { HttpApi, HttpApiBuilder, HttpApiEndpoint, HttpApiGroup, HttpApiScalar } from "effect/http-api"
import { createServer } from "node:http"
const User = Schema.Struct({
id: Schema.Int,
name: Schema.String
})
const Api = HttpApi.make("MyApi")
.add(
HttpApiGroup.make("Users")
.add(
HttpApiEndpoint.get("getUsers", "/users", {
success: Schema.Array(User)
}),
// a GET endpoint with a parameter ":id"
HttpApiEndpoint.get("getUser", "/user/:id", {
params: {
// ┌─── schema for the "id" parameter
// ▼
id: Schema.Int
},
success: User
})
)
)
const GroupLayer = HttpApiBuilder.group(
Api,
"Users",
(handlers) =>
handlers.handleAll({
getUsers: () =>
Effect.succeed(
[{ id: 1, name: "User 1" }, { id: 2, name: "User 2" }]
),
getUser: (ctx) => {
// ┌─── number
// ▼
const id = ctx.params.id
return Effect.succeed({ id, name: `User ${id}` })
}
})
)
const ApiLayer = HttpApiBuilder.layer(Api).pipe(
Layer.provide(GroupLayer),
Layer.provide(HttpApiScalar.layer(Api)),
HttpRouter.serve,
Layer.provide(NodeHttpServer.layer(createServer, { port: 3000 }))
)
Layer.launch(ApiLayer).pipe(NodeRuntime.runMain)
Catch-All Endpoints
Set the path to "*" to match any URL that no other endpoint handles. This is useful for custom "not found" pages or fallback responses.
Example (Defining a Catch-All Endpoint)
import { NodeHttpServer, NodeRuntime } from "@effect/platform-node"
import { Effect, Layer, Schema } from "effect"
import { HttpRouter } from "effect/http"
import { HttpApi, HttpApiBuilder, HttpApiEndpoint, HttpApiGroup, HttpApiScalar } from "effect/http-api"
import { createServer } from "node:http"
const User = Schema.Struct({
id: Schema.Int,
name: Schema.String
})
const IdParam = Schema.Int
const Api = HttpApi.make("MyApi")
.add(
HttpApiGroup.make("Users")
.add(
HttpApiEndpoint.get("getUsers", "/users", {
success: Schema.Array(User)
}),
HttpApiEndpoint.get("getUser", "/user/:id", {
params: {
id: IdParam
},
success: User
}),
HttpApiEndpoint.post("createUser", "/user", {
payload: User,
success: User
}),
HttpApiEndpoint.delete("deleteUser", "/user/:id", {
params: {
id: IdParam
}
}),
HttpApiEndpoint.patch("updateUser", "/user/:id", {
params: {
id: IdParam
},
payload: Schema.Struct({
name: Schema.String
}),
success: User
}),
// catch-all endpoint
HttpApiEndpoint.get("catchAll", "*", {
success: Schema.String
})
)
)
const GroupLayer = HttpApiBuilder.group(
Api,
"Users",
(handlers) =>
handlers.handleAll({
getUsers: () =>
Effect.succeed(
[{ id: 1, name: "User 1" }, { id: 2, name: "User 2" }]
),
getUser: (ctx) => {
const id = ctx.params.id
return Effect.succeed({ id, name: `User ${id}` })
},
createUser: (ctx) => {
const user = ctx.payload
return Effect.succeed(user)
},
deleteUser: (ctx) => {
const id = ctx.params.id
return Effect.log(`Deleting user ${id}`)
},
updateUser: (ctx) => {
const id = ctx.params.id
return Effect.succeed({ id, name: `User ${id}` })
},
catchAll: () => {
return Effect.succeed("Not found")
}
})
)
const ApiLayer = HttpApiBuilder.layer(Api).pipe(
Layer.provide(GroupLayer),
Layer.provide(HttpApiScalar.layer(Api)),
HttpRouter.serve,
Layer.provide(NodeHttpServer.layer(createServer, { port: 3000 }))
)
Layer.launch(ApiLayer).pipe(NodeRuntime.runMain)
Important
The catch-all endpoint must be the last endpoint in the group.
Important
(OpenAPI). A catch-all endpoint is not included in the OpenAPI specification because can't be represented as a path.
Prefixing
Prefixes let you prepend a common path segment to endpoints, groups, or an entire API. This avoids repeating the same base path on every endpoint.
Example (Using Prefixes for Common Path Management)
import { NodeHttpServer, NodeRuntime } from "@effect/platform-node"
import { Effect, Layer, Schema } from "effect"
import { HttpRouter } from "effect/http"
import { HttpApi, HttpApiBuilder, HttpApiEndpoint, HttpApiGroup, HttpApiScalar } from "effect/http-api"
import { createServer } from "node:http"
const Api = HttpApi.make("MyApi")
.add(
HttpApiGroup.make("group")
.add(
HttpApiEndpoint.get("endpointA", "/a", {
success: Schema.String
})
// Prefix for this endpoint
.prefix("/endpointPrefix"),
HttpApiEndpoint.get("endpointB", "/b", {
success: Schema.String
})
)
// Prefix for all endpoints in the group
.prefix("/groupPrefix")
)
// Prefix for the entire API
.prefix("/apiPrefix")
const GroupLayer = HttpApiBuilder.group(
Api,
"group",
(handlers) =>
handlers.handleAll({
endpointA: () => Effect.succeed("Endpoint A"),
endpointB: () => Effect.succeed("Endpoint B")
})
)
const ApiLayer = HttpApiBuilder.layer(Api).pipe(
Layer.provide(GroupLayer),
Layer.provide(HttpApiScalar.layer(Api)),
HttpRouter.serve,
Layer.provide(NodeHttpServer.layer(createServer, { port: 3000 }))
)
Layer.launch(ApiLayer).pipe(NodeRuntime.runMain)
You can test this endpoint using a GET request. For example:
curl http://localhost:3000/apiPrefix/groupPrefix/endpointPrefix/a # Returns 200 OK
curl http://localhost:3000/apiPrefix/groupPrefix/b # Returns 200 OK
Request
Query Parameters
Query parameters are the ?key=value pairs appended to a URL. Use the query option to declare a record of fields or a full schema — the framework will parse, validate, and type them for you.
Example (Defining Query Parameters with Metadata)
import { NodeHttpServer, NodeRuntime } from "@effect/platform-node"
import { Effect, Layer, Schema } from "effect"
import { HttpRouter } from "effect/http"
import { HttpApi, HttpApiBuilder, HttpApiEndpoint, HttpApiGroup, HttpApiScalar } from "effect/http-api"
import { createServer } from "node:http"
const User = Schema.Struct({
id: Schema.Int,
name: Schema.String
})
const Page = Schema.Int.check(Schema.isGreaterThan(0))
const Api = HttpApi.make("MyApi")
.add(
HttpApiGroup.make("Users")
.add(
HttpApiEndpoint.get("getUsers", "/users", {
success: Schema.Array(User),
// Specify a schema for each query parameter
query: {
// Parameter "page" for pagination
page: Schema.optionalKey(Page),
// Parameter "sort" for sorting options
sort: Schema.optionalKey(Schema.Literals(["id", "name"]))
}
})
)
)
const GroupLayer = HttpApiBuilder.group(
Api,
"Users",
(handlers) =>
handlers
.handle("getUsers", (ctx) => {
const { page, sort } = ctx.query
console.log(`Getting users with page ${page} and sort ${sort}`)
return Effect.succeed(
[{ id: 1, name: "User 1" }, { id: 2, name: "User 2" }]
)
})
)
const ApiLayer = HttpApiBuilder.layer(Api).pipe(
Layer.provide(GroupLayer),
Layer.provide(HttpApiScalar.layer(Api)),
HttpRouter.serve,
Layer.provide(NodeHttpServer.layer(createServer, { port: 3000 }))
)
Layer.launch(ApiLayer).pipe(NodeRuntime.runMain)
Defining an Array of Values for a Query Parameter
A single query parameter can carry multiple values (e.g., ?a=1&a=2). Wrap the parameter's schema in Schema.Array to accept an array of values.
Example (Defining an Array of String Values for a Query Parameter)
import { NodeHttpServer, NodeRuntime } from "@effect/platform-node"
import { Effect, Layer, Schema } from "effect"
import { HttpRouter } from "effect/http"
import { HttpApi, HttpApiBuilder, HttpApiEndpoint, HttpApiGroup, HttpApiScalar } from "effect/http-api"
import { createServer } from "node:http"
const User = Schema.Struct({
id: Schema.Int,
name: Schema.String
})
const Api = HttpApi.make("MyApi")
.add(
HttpApiGroup.make("Users")
.add(
HttpApiEndpoint.get("getUsers", "/users", {
success: Schema.Array(User),
query: {
a: Schema.optionalKey(Schema.Array(Schema.String))
}
})
)
)
const GroupLayer = HttpApiBuilder.group(
Api,
"Users",
(handlers) =>
handlers
.handle("getUsers", (ctx) => {
console.log(ctx.query)
return Effect.succeed(
[{ id: 1, name: "User 1" }, { id: 2, name: "User 2" }]
)
})
)
const ApiLayer = HttpApiBuilder.layer(Api).pipe(
Layer.provide(GroupLayer),
Layer.provide(HttpApiScalar.layer(Api)),
HttpRouter.serve,
Layer.provide(NodeHttpServer.layer(createServer, { port: 3000 }))
)
Layer.launch(ApiLayer).pipe(NodeRuntime.runMain)
You can test this endpoint by passing an array of values in the query string. For example:
curl "http://localhost:3000/users?a=1&a=2" # Two values for the `a` parameter
The query string sends two values (1 and 2) for the a parameter. The server will process and validate these values according to the schema.
Both the following requests will be valid:
curl "http://localhost:3000/users" # No values for the `a` parameter
curl "http://localhost:3000/users?a=1" # One value for the `a` parameter
Request Headers
Use the headers option to declare a record of fields or a full schema for the request headers the endpoint expects.
Important
All headers are normalized to lowercase. Always use lowercase keys for the headers.
Example (Describe and validate custom headers)
import { NodeHttpServer, NodeRuntime } from "@effect/platform-node"
import { Effect, Layer, Schema } from "effect"
import { HttpRouter } from "effect/http"
import { HttpApi, HttpApiBuilder, HttpApiEndpoint, HttpApiGroup, HttpApiScalar } from "effect/http-api"
import { createServer } from "node:http"
const User = Schema.Struct({
id: Schema.Int,
name: Schema.String
})
const Api = HttpApi.make("MyApi")
.add(
HttpApiGroup.make("Users")
.add(
HttpApiEndpoint.get("getUsers", "/users", {
// Always use lowercase keys for the headers
headers: {
"x-api-key": Schema.String,
"x-request-id": Schema.String
},
success: Schema.Array(User)
})
)
)
const GroupLayer = HttpApiBuilder.group(
Api,
"Users",
(handlers) =>
handlers.handle("getUsers", () =>
Effect.succeed(
[{ id: 1, name: "User 1" }, { id: 2, name: "User 2" }]
))
)
const ApiLayer = HttpApiBuilder.layer(Api).pipe(
Layer.provide(GroupLayer),
Layer.provide(HttpApiScalar.layer(Api)),
HttpRouter.serve,
Layer.provide(NodeHttpServer.layer(createServer, { port: 3000 }))
)
Layer.launch(ApiLayer).pipe(NodeRuntime.runMain)
You can test the endpoint by sending the headers:
curl -H "X-API-Key: 1234567890" -H "X-Request-ID: 1234567890" http://localhost:3000/users
The server validates these headers against the declared schema before handling the request.
Handling Multipart Requests
To accept file uploads, mark the payload as multipart with HttpApiSchema.asMultipart. Use Multipart.FilesSchema for the file fields — uploaded files will be persisted to disk automatically.
Example (Defining an Endpoint for File Uploads)
import { NodeHttpServer, NodeRuntime } from "@effect/platform-node"
import { Effect, Layer, Schema } from "effect"
import { HttpRouter, Multipart } from "effect/http"
import { HttpApi, HttpApiBuilder, HttpApiEndpoint, HttpApiGroup, HttpApiScalar, HttpApiSchema } from "effect/http-api"
import { createServer } from "node:http"
const Api = HttpApi.make("MyApi")
.add(
HttpApiGroup.make("Users")
.add(
HttpApiEndpoint.post("upload", "/users/upload", {
// Specify that the payload is a multipart request
payload: HttpApiSchema.asMultipart(
Schema.Struct({
// Define a "files" field to handle file uploads
files: Multipart.FilesSchema
})
),
success: Schema.String
})
)
)
const GroupLayer = HttpApiBuilder.group(
Api,
"Users",
(handlers) =>
handlers
.handle("upload", (ctx) => {
// ┌─── readonly Multipart.PersistedFile[]
// ▼
const { files } = ctx.payload
console.log(files)
return Effect.succeed("Uploaded")
})
)
const ApiLayer = HttpApiBuilder.layer(Api).pipe(
Layer.provide(GroupLayer),
Layer.provide(HttpApiScalar.layer(Api)),
HttpRouter.serve,
Layer.provide(NodeHttpServer.layer(createServer, { port: 3000 }))
)
Layer.launch(ApiLayer).pipe(NodeRuntime.runMain)
You can test this endpoint by sending a multipart request with a file upload. For example:
echo "Sample file content" | curl -X POST -F "files=@-" http://localhost:3000/users/upload
Changing the Request Encoding
By default, request bodies are JSON. To accept a different format — like form-urlencoded data — pipe the payload schema through the appropriate HttpApiSchema.as* helper.
Example (Customizing Request Encoding)
import { NodeHttpServer, NodeRuntime } from "@effect/platform-node"
import { Effect, Layer, Schema } from "effect"
import { HttpRouter } from "effect/http"
import { HttpApi, HttpApiBuilder, HttpApiEndpoint, HttpApiGroup, HttpApiScalar, HttpApiSchema } from "effect/http-api"
import { createServer } from "node:http"
const User = Schema.Struct({
id: Schema.Int,
name: Schema.String
})
const Api = HttpApi.make("MyApi")
.add(
HttpApiGroup.make("Users")
.add(
HttpApiEndpoint.post("createUser", "/user", {
// Set the request payload as a string encoded with query parameters
payload: Schema.Struct({
id: Schema.Int,
name: Schema.String
})
// Specify the encoding as form url encoded
.pipe(HttpApiSchema.asFormUrlEncoded()),
success: User
})
)
)
const GroupLayer = HttpApiBuilder.group(
Api,
"Users",
(handlers) =>
handlers
.handle("createUser", (ctx) => {
const user = ctx.payload
return Effect.succeed(user)
})
)
const ApiLayer = HttpApiBuilder.layer(Api).pipe(
Layer.provide(GroupLayer),
Layer.provide(HttpApiScalar.layer(Api)),
HttpRouter.serve,
Layer.provide(NodeHttpServer.layer(createServer, { port: 3000 }))
)
Layer.launch(ApiLayer).pipe(NodeRuntime.runMain)
You can test this endpoint using a URL-encoded request body. For example:
curl http://localhost:3000/user \
--request POST \
--header 'Accept: */*' \
--header 'Content-Type: application/x-www-form-urlencoded' \
--data-urlencode 'id=1' \
--data-urlencode 'name=John'
Accessing the HttpServerRequest
Inside a handler, ctx.request gives you access to the raw incoming HTTP request. Use this when you need low-level details not covered by the endpoint schema (e.g., the HTTP method or raw URL).
Example (Accessing the Request Object in a GET Endpoint)
import { NodeHttpServer, NodeRuntime } from "@effect/platform-node"
import { Effect, Layer, Schema } from "effect"
import { HttpRouter } from "effect/http"
import { HttpApi, HttpApiBuilder, HttpApiEndpoint, HttpApiGroup } from "effect/http-api"
import { createServer } from "node:http"
const Api = HttpApi.make("MyApi").add(
HttpApiGroup.make("Greetings").add(
HttpApiEndpoint.get("hello", "/", {
success: Schema.String
})
)
)
const GroupLayer = HttpApiBuilder.group(
Api,
"Greetings",
(handlers) =>
handlers.handle(
"hello",
(ctx) => {
// ┌─── HttpServerRequest
// ▼
const req = ctx.request
// Access the request method
console.log(req.method)
return Effect.succeed("Hello, World!")
}
)
)
const ApiLayer = HttpApiBuilder.layer(Api).pipe(
Layer.provide(GroupLayer),
HttpRouter.serve,
Layer.provide(NodeHttpServer.layer(createServer, { port: 3000 }))
)
Layer.launch(ApiLayer).pipe(NodeRuntime.runMain)
Validating Request Cookies
There is no cookies option on endpoints. Instead, validated cookie access goes through the security middleware system: define an HttpApiSecurity.apiKey with in: "cookie" and attach it to a middleware. The cookie value is decoded and handed to your security handler as a Redacted credential.
Example (Validating a Session Cookie)
import { NodeHttpServer, NodeRuntime } from "@effect/platform-node"
import { Context, Effect, Layer, Redacted, Schema } from "effect"
import { HttpRouter } from "effect/http"
import {
HttpApi,
HttpApiBuilder,
HttpApiEndpoint,
HttpApiGroup,
HttpApiMiddleware,
HttpApiScalar,
HttpApiSecurity
} from "effect/http-api"
import { createServer } from "node:http"
// Define the service providing the current user
class CurrentUser
extends Context.Service<CurrentUser, { readonly id: number; readonly name: string }>()("CurrentUser")
{}
// Define the security scheme: read the "session" cookie
const sessionCookie = HttpApiSecurity.apiKey({ in: "cookie", key: "session" })
class Auth extends HttpApiMiddleware.Service<Auth, {
provides: CurrentUser
}>()("Auth", {
error: Schema.String.annotate({
httpApiStatus: 401,
description: "Auth error"
}),
security: { session: sessionCookie }
}) {}
const Api = HttpApi.make("api").add(
HttpApiGroup.make("group")
.add(
HttpApiEndpoint.get("me", "/me", {
success: Schema.Struct({ id: Schema.Finite })
})
)
.middleware(Auth)
)
const AuthLayer = Layer.succeed(
Auth,
{
session: (effect, opts) =>
Effect.provideServiceEffect(
effect,
CurrentUser,
Effect.gen(function*() {
const value = Redacted.value(opts.credential)
if (value !== "valid-session") {
return yield* Effect.fail("Invalid session")
}
return { id: 1, name: "John Doe" }
})
)
}
)
const GroupLayer = HttpApiBuilder.group(
Api,
"group",
(handlers) =>
handlers.handle("me", () =>
Effect.gen(function*() {
const user = yield* CurrentUser
return { id: user.id }
}))
).pipe(Layer.provide(AuthLayer))
const ApiLayer = HttpApiBuilder.layer(Api).pipe(
Layer.provide(GroupLayer),
Layer.provide(HttpApiScalar.layer(Api)),
HttpRouter.serve,
Layer.provide(NodeHttpServer.layer(createServer, { port: 3000 }))
)
Layer.launch(ApiLayer).pipe(NodeRuntime.runMain)
// Valid session:
// curl "http://localhost:3000/me" --cookie "session=valid-session"
// {"id":1}
//
// Invalid session:
// curl "http://localhost:3000/me" --cookie "session=wrong"
// "Invalid session"
For quick, unvalidated access you can read cookies directly from ctx.request.cookies inside any handler. These cookies won't appear in the OpenAPI spec.
Example (Reading Cookies Directly in a Handler)
import { NodeHttpServer, NodeRuntime } from "@effect/platform-node"
import { Effect, Layer, Schema } from "effect"
import { HttpRouter } from "effect/http"
import { HttpApi, HttpApiBuilder, HttpApiEndpoint, HttpApiGroup } from "effect/http-api"
import { createServer } from "node:http"
const Api = HttpApi.make("api").add(
HttpApiGroup.make("group").add(
HttpApiEndpoint.get("me", "/me", {
success: Schema.String
})
)
)
const GroupLayer = HttpApiBuilder.group(
Api,
"group",
(handlers) =>
handlers.handle("me", (ctx) => {
const lang = ctx.request.cookies.lang ?? "en"
return Effect.succeed(`Language: ${lang}`)
})
)
const ApiLayer = HttpApiBuilder.layer(Api).pipe(
Layer.provide(GroupLayer),
HttpRouter.serve,
Layer.provide(NodeHttpServer.layer(createServer, { port: 3000 }))
)
Layer.launch(ApiLayer).pipe(NodeRuntime.runMain)
// curl "http://localhost:3000/me" --cookie "lang=it"
// "Language: it"
Streaming Requests
To receive large or continuous data from the client, register the endpoint with .handleRaw, which opts out of automatic payload decoding and exposes the raw HttpServerRequest. The request body is then available as a Stream of Uint8Array chunks through request.stream, so the handler can consume it incrementally instead of buffering it in memory.
The payload schema still describes the endpoint in the generated documentation, but with .handleRaw the handler decides how the body is consumed. Note that the declared content type is no longer enforced at runtime: requests with a different Content-Type header are not rejected with 415, so any such validation is up to the handler.
Example (Handling Streaming Requests)
import { NodeHttpServer, NodeRuntime } from "@effect/platform-node"
import { Effect, Layer, Schema, Stream } from "effect"
import { HttpRouter } from "effect/http"
import { HttpApi, HttpApiBuilder, HttpApiEndpoint, HttpApiGroup, HttpApiSchema } from "effect/http-api"
import { createServer } from "node:http"
const Api = HttpApi.make("myApi").add(
HttpApiGroup.make("group").add(
HttpApiEndpoint.post("acceptStream", "/stream", {
// Define the payload as a Uint8Array with a specific encoding
payload: Schema.Uint8Array.pipe(
HttpApiSchema.asUint8Array() // default content type: application/octet-stream
),
success: Schema.String
})
)
)
const GroupLayer = HttpApiBuilder.group(
Api,
"group",
(handlers) =>
// Use `handleRaw` to opt out of payload decoding and access the raw request
handlers.handleRaw("acceptStream", (ctx) =>
// Consume the request body as a stream of Uint8Array chunks
ctx.request.stream.pipe(
// Fold over the chunks as they arrive, without buffering the body
Stream.runFold(() => 0, (total, chunk) => total + chunk.length),
Effect.map((total) => `received ${total} bytes`),
// `request.stream` fails with `HttpServerError`, which the endpoint
// does not declare, so treat it as a defect
Effect.orDie
))
)
const ApiLayer = HttpApiBuilder.layer(Api).pipe(
Layer.provide(GroupLayer),
HttpRouter.serve,
Layer.provide(NodeHttpServer.layer(createServer, { port: 3000 }))
)
Layer.launch(ApiLayer).pipe(NodeRuntime.runMain)
You can test the streaming request using curl or any tool that supports sending binary data. For example:
printf 'abc' | curl -X POST 'http://localhost:3000/stream' --data-binary @- -H "Content-Type: application/octet-stream"
# Output: "received 3 bytes"
Response
Status Codes
Success responses default to 200 OK. To use a different status code, annotate the success schema with HttpApiSchema.status(code) or set the httpApiStatus annotation.
Example (Defining a GET Endpoint with a custom status code)
import { NodeHttpServer, NodeRuntime } from "@effect/platform-node"
import { Effect, Layer, Schema } from "effect"
import { HttpRouter } from "effect/http"
import { HttpApi, HttpApiBuilder, HttpApiEndpoint, HttpApiGroup, HttpApiScalar, HttpApiSchema } from "effect/http-api"
import { createServer } from "node:http"
const User = Schema.Struct({
id: Schema.Int,
name: Schema.String
})
const Api = HttpApi.make("MyApi")
.add(
HttpApiGroup.make("Users")
.add(
HttpApiEndpoint.get("getUsers", "/users", {
success: Schema.Array(User)
.pipe(HttpApiSchema.status(206))
})
)
)
const GroupLayer = HttpApiBuilder.group(
Api,
"Users",
(handlers) =>
handlers
.handle("getUsers", () => {
return Effect.succeed(
[{ id: 1, name: "User 1" }, { id: 2, name: "User 2" }]
)
})
)
const ApiLayer = HttpApiBuilder.layer(Api).pipe(
Layer.provide(GroupLayer),
Layer.provide(HttpApiScalar.layer(Api)),
HttpRouter.serve,
Layer.provide(NodeHttpServer.layer(createServer, { port: 3000 }))
)
Layer.launch(ApiLayer).pipe(NodeRuntime.runMain)
Changing the Response Encoding
Responses default to JSON. To return a different format — like CSV or plain text — pipe the success schema through the matching HttpApiSchema.as* helper and, optionally, set a custom contentType.
Example (Returning Data as text/csv)
import { NodeHttpServer, NodeRuntime } from "@effect/platform-node"
import { Effect, Layer, Schema } from "effect"
import { HttpRouter } from "effect/http"
import { HttpApi, HttpApiBuilder, HttpApiEndpoint, HttpApiGroup, HttpApiScalar, HttpApiSchema } from "effect/http-api"
import { createServer } from "node:http"
const Api = HttpApi.make("MyApi")
.add(
HttpApiGroup.make("Users")
.add(
HttpApiEndpoint.get("csv", "/users/csv", {
success: Schema.String.pipe(
// Set the success response as a string with CSV encoding
HttpApiSchema.asText({
// Define the content type as text/csv
contentType: "text/csv"
})
)
})
)
)
const GroupLayer = HttpApiBuilder.group(
Api,
"Users",
(handlers) =>
handlers
.handle("csv", (ctx) => {
return Effect.succeed("id,name\n1,John\n2,Jane")
})
)
const ApiLayer = HttpApiBuilder.layer(Api).pipe(
Layer.provide(GroupLayer),
Layer.provide(HttpApiScalar.layer(Api)),
HttpRouter.serve,
Layer.provide(NodeHttpServer.layer(createServer, { port: 3000 }))
)
Layer.launch(ApiLayer).pipe(NodeRuntime.runMain)
You can test this endpoint using a GET request. For example:
curl http://localhost:3000/users/csv
The following encodings are supported:
Jsonthe default encoding (default content type:application/json)Uint8Arraythe encoding for binary data (default content type:application/octet-stream)Textthe encoding for text data (default content type:text/plain)
Setting Response Headers
Response headers can be declared in the endpoint's schemas, so they are type-checked on the server, rendered in the OpenAPI documentation, and decoded by the derived client. Two mechanisms are available:
HttpApiSchema.WithHeaders(schema, headers)wraps a response schema together with a headers schema. Handlers return the body and headers as a pair. Recommended for success responses, including streams.HttpApiSchema.encodeToWithHeadersfolds headers into an opaque domain type such as an error class, so handlers keep working with plain domain values.
Only one response schema carrying headers may be declared for each status, though plain responses with different content types may share that status.
For headers that are not part of the API contract, HttpEffect.appendPreResponseHandler remains available as an untyped escape hatch.
Declaring Response Headers with WithHeaders
Wrap the success schema with HttpApiSchema.WithHeaders(schema, headers). The headers argument accepts a fields shorthand (as below) or any schema, mirroring the request-side headers option. The handler then returns a value built with HttpApiSchema.withHeaders({ body, headers }).
Example (Declaring a Response Header on a Success Schema)
import { NodeHttpServer, NodeRuntime } from "@effect/platform-node"
import { Effect, Layer, Schema } from "effect"
import { HttpRouter } from "effect/http"
import { HttpApi, HttpApiBuilder, HttpApiEndpoint, HttpApiGroup, HttpApiSchema } from "effect/http-api"
import { createServer } from "node:http"
const User = Schema.Struct({
id: Schema.Int,
name: Schema.String
})
const Api = HttpApi.make("MyApi").add(
HttpApiGroup.make("Users").add(
HttpApiEndpoint.get("getUsers", "/users", {
// Wrap the success schema with a response headers schema
success: HttpApiSchema.WithHeaders(Schema.Array(User), {
"x-total-count": Schema.Int
})
})
)
)
const GroupLayer = HttpApiBuilder.group(
Api,
"Users",
(handlers) =>
handlers.handle("getUsers", () =>
// Return the body together with the declared headers
Effect.succeed(HttpApiSchema.withHeaders({
body: [{ id: 1, name: "John" }],
headers: { "x-total-count": 1 }
})))
)
const ApiLayer = HttpApiBuilder.layer(Api).pipe(
Layer.provide(GroupLayer),
HttpRouter.serve,
Layer.provide(NodeHttpServer.layer(createServer, { port: 3000 }))
)
Layer.launch(ApiLayer).pipe(NodeRuntime.runMain)
// curl -v "http://localhost:3000/users" 2>&1 | grep -i "x-total-count"
// < x-total-count: 1
The derived client detects the wrapper and returns the same shape, with the headers decoded through the headers schema:
const users = yield * client.Users.getUsers()
users.body // => [{ id: 1, name: "John" }]
users.headers // => { "x-total-count": 1 }
Things to know:
- Header values are converted to strings at the HTTP boundary, the same way as request headers, params, and query.
Schema.Intgoes out as"1"and decodes back to1on the client.undefinedvalues are omitted from the response. - Status and encoding annotations resolve from the wrapper first, then fall through to the inner schema, so
HttpApiSchema.WithHeaders(User.pipe(HttpApiSchema.status(201)), ...)responds with201. - Declared headers are applied after the body is encoded and override headers set by the encoding on collision, including
content-type. - Stream success schemas (
HttpApiSchema.StreamSse,HttpApiSchema.StreamUint8Array) can be wrapped too. Headers are encoded before the response starts streaming, and the client resolves to a value whosebodyis the stream. WithHeadersis also allowed on error schemas, in which case the handler fails with the wrapped value. For errors,encodeToWithHeaders(below) is usually more convenient because handlers can fail with the domain error directly.
Folding Headers into Domain Types with encodeToWithHeaders
HttpApiSchema.encodeToWithHeaders encodes a schema as a { body, headers } pair while its Type stays unchanged. This lets an error class carry data that travels in a response header: handlers fail with plain error instances, and the client receives the same class with the header folded back in.
The body schema is authoritative for everything wire-level: status, content type, and response encoding resolve from the body schema's annotations. A status annotation on the source schema stops mattering once wrapped, so spell the status on the body — HttpApiSchema.Empty(404) declares an empty body with status 404.
Example (Returning an Error With a Response Header)
import { NodeHttpServer, NodeRuntime } from "@effect/platform-node"
import { Effect, Layer, Schema } from "effect"
import { HttpRouter } from "effect/http"
import { HttpApi, HttpApiBuilder, HttpApiEndpoint, HttpApiGroup, HttpApiSchema } from "effect/http-api"
import { createServer } from "node:http"
class UserNotFound extends Schema.TaggedError<UserNotFound>()("UserNotFound", {
userId: Schema.Int
}) {}
const UserNotFoundWithHeaders = UserNotFound.pipe(
HttpApiSchema.encodeToWithHeaders({
// The body schema is authoritative for status and content type
body: HttpApiSchema.Empty(404),
headers: {
"x-user-id": Schema.Int
}
}, {
// Pure mappings between the domain type and the { body, headers } pair
decode: ({ headers }) => new UserNotFound({ userId: headers["x-user-id"] }),
encode: (error) => ({
headers: { "x-user-id": error.userId },
body: undefined
})
})
)
const User = Schema.Struct({
id: Schema.Int,
name: Schema.String
})
const Api = HttpApi.make("MyApi").add(
HttpApiGroup.make("Users").add(
HttpApiEndpoint.get("getUser", "/user/:id", {
params: {
id: Schema.Int
},
success: User,
error: UserNotFoundWithHeaders
})
)
)
const GroupLayer = HttpApiBuilder.group(
Api,
"Users",
(handlers) =>
handlers.handle("getUser", (ctx) => {
const id = ctx.params.id
if (id === 1) {
// Fail with the plain error instance
return Effect.fail(new UserNotFound({ userId: id }))
}
return Effect.succeed({ id, name: `User ${id}` })
})
)
const ApiLayer = HttpApiBuilder.layer(Api).pipe(
Layer.provide(GroupLayer),
HttpRouter.serve,
Layer.provide(NodeHttpServer.layer(createServer, { port: 3000 }))
)
Layer.launch(ApiLayer).pipe(NodeRuntime.runMain)
// curl -v "http://localhost:3000/user/1" 2>&1 | grep -i "x-user-id"
// < x-user-id: 1
The decode/encode mappings are pure total functions: validation lives in the body and headers schemas, the mappings only reshape valid data. The error channel is unchanged — a client calling this endpoint fails with a UserNotFound instance whose userId was decoded from the header.
encodeToWithHeaders also works on custom success types, but avoid burying stream schemas in it; wrap streams with WithHeaders instead so the generated client keeps the stream's error channel.
Untyped Response Headers
For headers that should not appear in the API contract, call HttpEffect.appendPreResponseHandler inside your handler. The callback receives the request and response objects and must return the updated response. These headers bypass the schemas, the OpenAPI documentation, and the derived client.
Example (Adding a Custom Response Header)
import { NodeHttpServer, NodeRuntime } from "@effect/platform-node"
import { Effect, Layer, Schema } from "effect"
import { HttpEffect, HttpRouter, HttpServerResponse } from "effect/http"
import { HttpApi, HttpApiBuilder, HttpApiEndpoint, HttpApiGroup } from "effect/http-api"
import { createServer } from "node:http"
const Api = HttpApi.make("api").add(
HttpApiGroup.make("group").add(
HttpApiEndpoint.get("hello", "/hello", {
success: Schema.String
})
)
)
const GroupLayer = HttpApiBuilder.group(
Api,
"group",
(handlers) =>
handlers.handle("hello", () =>
Effect.gen(function*() {
yield* HttpEffect.appendPreResponseHandler((_req, response) =>
Effect.succeed(HttpServerResponse.setHeader(response, "x-custom", "hello"))
)
return "Hello, World!"
}))
)
const ApiLayer = HttpApiBuilder.layer(Api).pipe(
Layer.provide(GroupLayer),
HttpRouter.serve,
Layer.provide(NodeHttpServer.layer(createServer, { port: 3000 }))
)
Layer.launch(ApiLayer).pipe(NodeRuntime.runMain)
// curl -v "http://localhost:3000/hello" 2>&1 | grep -i "x-custom"
// < x-custom: hello
Setting Response Cookies
Set cookies on the response using HttpEffect.appendPreResponseHandler together with HttpServerResponse.setCookie. For cookies tied to an HttpApiSecurity.apiKey, use the shortcut HttpApiBuilder.securitySetCookie instead.
Example (Setting a Response Cookie)
import { NodeHttpServer, NodeRuntime } from "@effect/platform-node"
import { Effect, Layer, Schema } from "effect"
import { HttpEffect, HttpRouter, HttpServerResponse } from "effect/http"
import { HttpApi, HttpApiBuilder, HttpApiEndpoint, HttpApiGroup } from "effect/http-api"
import { createServer } from "node:http"
const Api = HttpApi.make("api").add(
HttpApiGroup.make("group").add(
HttpApiEndpoint.get("hello", "/hello", {
success: Schema.String
})
)
)
const GroupLayer = HttpApiBuilder.group(
Api,
"group",
(handlers) =>
handlers.handle("hello", () =>
Effect.gen(function*() {
yield* HttpEffect.appendPreResponseHandler((_req, response) =>
Effect.succeed(HttpServerResponse.setCookieUnsafe(response, "my-cookie", "my-value", {
httpOnly: true,
secure: true,
path: "/"
}))
)
return "Hello, World!"
}))
)
const ApiLayer = HttpApiBuilder.layer(Api).pipe(
Layer.provide(GroupLayer),
HttpRouter.serve,
Layer.provide(NodeHttpServer.layer(createServer, { port: 3000 }))
)
Layer.launch(ApiLayer).pipe(NodeRuntime.runMain)
// curl -v "http://localhost:3000/hello" 2>&1 | grep -i "set-cookie"
// < set-cookie: my-cookie=my-value; Path=/; HttpOnly; Secure
Redirects
To redirect the client to a different URL, return an HttpServerResponse.redirect from the handler. The redirect is not modeled in the schema — the endpoint definition stays as "no content".
import { NodeHttpServer, NodeRuntime } from "@effect/platform-node"
import { Effect, Layer, Schema } from "effect"
import { HttpRouter } from "effect/http"
import { HttpServerResponse } from "effect/http"
import { HttpApi, HttpApiBuilder, HttpApiEndpoint, HttpApiGroup, HttpApiScalar } from "effect/http-api"
import { createServer } from "node:http"
const Api = HttpApi.make("MyApi").add(
HttpApiGroup.make("group").add(
HttpApiEndpoint.get("newPage", "/new", {
success: Schema.String
}),
// Schema-wise this is just "no content" (redirect headers aren't modeled here)
HttpApiEndpoint.get("oldPage", "/old")
)
)
const GroupLayer = HttpApiBuilder.group(
Api,
"group",
(handlers) =>
handlers.handleAll({
newPage: () => Effect.succeed("You are on /new"),
oldPage: () =>
Effect.succeed(
HttpServerResponse.redirect("/new", { status: 302 })
)
})
)
const ApiLayer = HttpApiBuilder.layer(Api).pipe(
Layer.provide(GroupLayer),
Layer.provide(HttpApiScalar.layer(Api)),
HttpRouter.serve,
Layer.provide(NodeHttpServer.layer(createServer, { port: 3000 }))
)
Layer.launch(ApiLayer).pipe(NodeRuntime.runMain)
// curl "http://localhost:3000/old" -L
Streaming Responses
To stream data to the client over time, declare the success schema with one of the streaming constructors:
HttpApiSchema.StreamUint8Array()streams raw bytes (default content type:application/octet-stream)HttpApiSchema.StreamSse(options)streams typed Server-Sent Events (default content type:text/event-stream)
With a streaming success schema, the handler returns a Stream directly, and the derived client resolves to a typed Stream on the consuming side. The stream declaration is also rendered in the OpenAPI documentation.
Streaming Raw Bytes
HttpApiSchema.StreamUint8Array declares a binary streaming response. The handler returns a Stream<Uint8Array> that emits chunks at whatever pace you choose.
Example (Implementing a Binary Streaming Endpoint)
import { NodeHttpServer, NodeRuntime } from "@effect/platform-node"
import { Effect, Layer, Schedule, Stream } from "effect"
import { HttpRouter } from "effect/http"
import { HttpApi, HttpApiBuilder, HttpApiEndpoint, HttpApiGroup, HttpApiSchema } from "effect/http-api"
import { createServer } from "node:http"
const Api = HttpApi.make("myApi").add(
HttpApiGroup.make("group").add(
HttpApiEndpoint.get("getStream", "/stream", {
// Declare a streaming success response
// (default content type: application/octet-stream)
success: HttpApiSchema.StreamUint8Array()
})
)
)
// Simulate a stream of data
const stream = Stream.make("a", "b", "c").pipe(
Stream.schedule(Schedule.spaced("500 millis")),
Stream.map((s) => new TextEncoder().encode(s))
)
const GroupLayer = HttpApiBuilder.group(
Api,
"group",
(handlers) =>
handlers.handle(
"getStream",
// Return the stream directly from the handler
() => Effect.succeed(stream)
)
)
const ApiLayer = HttpApiBuilder.layer(Api).pipe(
Layer.provide(GroupLayer),
HttpRouter.serve,
Layer.provide(NodeHttpServer.layer(createServer, { port: 3000 }))
)
Layer.launch(ApiLayer).pipe(NodeRuntime.runMain)
You can test the streaming response using curl or any similar HTTP client that supports streaming:
curl 'http://localhost:3000/stream' --no-buffer
The response will stream data (a, b, c) with a 500ms interval between each item.
Streaming Server-Sent Events
HttpApiSchema.StreamSse declares a Server-Sent Events response. Pass a data schema to stream plain values: each stream element is JSON-encoded into the data field of an SSE event on the way out, and the derived client decodes it back to the value.
Example (Implementing an SSE Endpoint)
import { NodeHttpServer, NodeRuntime } from "@effect/platform-node"
import { Effect, Layer, Schedule, Schema, Stream } from "effect"
import { HttpRouter } from "effect/http"
import { HttpApi, HttpApiBuilder, HttpApiEndpoint, HttpApiGroup, HttpApiSchema } from "effect/http-api"
import { createServer } from "node:http"
const Message = Schema.Struct({
text: Schema.String
})
const Api = HttpApi.make("myApi").add(
HttpApiGroup.make("group").add(
HttpApiEndpoint.get("getEvents", "/events", {
// Each stream element is JSON-encoded into the `data` field of an SSE
// event (default content type: text/event-stream)
success: HttpApiSchema.StreamSse({ data: Message })
})
)
)
const GroupLayer = HttpApiBuilder.group(
Api,
"group",
(handlers) =>
handlers.handle("getEvents", () =>
Effect.succeed(
Stream.make({ text: "one" }, { text: "two" }, { text: "three" }).pipe(
Stream.schedule(Schedule.spaced("500 millis"))
)
))
)
const ApiLayer = HttpApiBuilder.layer(Api).pipe(
Layer.provide(GroupLayer),
HttpRouter.serve,
Layer.provide(NodeHttpServer.layer(createServer, { port: 3000 }))
)
Layer.launch(ApiLayer).pipe(NodeRuntime.runMain)
// curl 'http://localhost:3000/events' --no-buffer
// data: {"text":"one"}
//
// data: {"text":"two"}
//
// data: {"text":"three"}
To control the full event shape instead, pass an events schema whose Encoded side matches the SSE wire format: a required data string plus optional id and event fields. The handler then emits whole events.
Consuming Streams with the Derived Client
For both constructors, calling the endpoint on the derived client resolves to a typed Stream:
const events = yield * client.group.getEvents()
// events: Stream<{ readonly text: string }, ...>
yield * Stream.runForEach(events, (message) => Console.log(message.text))
Typed Stream Failures
HttpApiSchema.StreamSse accepts an error schema describing typed stream failures. Since the HTTP status is already sent when the stream fails, the failure cannot travel as a normal error response. Instead, the server encodes the full Cause into a reserved effect/http-api/stream/failure event, and the derived client decodes that event and fails the stream with the original cause.
Example (Declaring a Typed Stream Failure)
class StreamError extends Schema.TaggedError<StreamError>()("StreamError", {
reason: Schema.String
}) {}
const Api = HttpApi.make("myApi").add(
HttpApiGroup.make("group").add(
HttpApiEndpoint.get("getEvents", "/events", {
// The handler may return a Stream that fails with StreamError,
// and the client's stream fails with StreamError too
success: HttpApiSchema.StreamSse({ data: Message, error: StreamError })
})
)
)
Things to know:
- Set a custom status or content type with
HttpApiSchema.status(code)and thecontentTypeoption, for exampleHttpApiSchema.status(206)(HttpApiSchema.StreamUint8Array({ contentType: "application/custom-bytes" })). - Wrap a stream schema with
HttpApiSchema.WithHeadersto declare typed response headers (see Setting Response Headers). The handler returnsHttpApiSchema.withHeaders({ body, headers })with the stream asbody, and the client resolves to the same shape. - An endpoint may declare at most one streaming success schema,
HEADendpoints cannot declare one, and streaming schemas are not supported in error responses. - The
effect/http-api/stream/failureevent name is reserved:eventsschemas may not declare it, and the client treats such an event as a stream failure only when itsdatadecodes to aCause.
Error Handling
Adding Custom Error Responses
Endpoints can declare the errors they may return. Each error is a schema annotated with an HTTP status code via HttpApiSchema.status(code). The status is set once on the schema and reused wherever that schema appears. When your handler fails with a matching error, the framework serializes it and responds with the declared status.
Example (Defining Error Responses for an Endpoint)
import { NodeHttpServer, NodeRuntime } from "@effect/platform-node"
import { Effect, Layer, Schema } from "effect"
import { HttpRouter } from "effect/http"
import { HttpApi, HttpApiBuilder, HttpApiEndpoint, HttpApiGroup, HttpApiScalar, HttpApiSchema } from "effect/http-api"
import { createServer } from "node:http"
const User = Schema.Struct({
id: Schema.Int,
name: Schema.String
})
const UserNotFound = Schema.Struct({
_tag: Schema.tag("UserNotFound"),
message: Schema.String
}).pipe(HttpApiSchema.status(404))
const Unauthorized = Schema.Struct({
_tag: Schema.tag("Unauthorized")
}).pipe(HttpApiSchema.status(401))
const Api = HttpApi.make("MyApi")
.add(
HttpApiGroup.make("Users")
.add(
HttpApiEndpoint.get("getUser", "/user/:id", {
params: {
id: Schema.Int
},
success: User,
error: [UserNotFound, Unauthorized /** etc. */]
})
)
.add(
HttpApiEndpoint.delete("deleteUser", "/user/:id", {
params: {
id: Schema.Int
},
error: [UserNotFound, Unauthorized /** etc. */]
})
)
)
const GroupLayer = HttpApiBuilder.group(
Api,
"Users",
(handlers) =>
handlers.handleAll({
getUser: (ctx) => {
const id = ctx.params.id
if (id === 1) {
return Effect.fail(UserNotFound.make({ message: "User not found" }))
}
return Effect.succeed({ id, name: `User ${id}` })
},
deleteUser: (ctx) => {
const id = ctx.params.id
if (id === 1) {
return Effect.fail(UserNotFound.make({ message: "User not found" }))
}
return Effect.succeed(void 0)
}
})
)
const ApiLayer = HttpApiBuilder.layer(Api).pipe(
Layer.provide(GroupLayer),
Layer.provide(HttpApiScalar.layer(Api)),
HttpRouter.serve,
Layer.provide(NodeHttpServer.layer(createServer, { port: 3000 }))
)
Layer.launch(ApiLayer).pipe(NodeRuntime.runMain)
You can test these endpoints. For example:
curl http://localhost:3000/user/1 # Returns 404 Not Found
curl http://localhost:3000/user/2 # Returns 200 OK
curl -X DELETE http://localhost:3000/user/1 # Returns 404 Not Found
curl -X DELETE http://localhost:3000/user/2 # Returns 200 OK
Predefined Error Types
The HttpApiError module provides ready-made error schemas for common HTTP status codes (404, 401, etc.). Using these saves you from defining boilerplate error types and keeps error handling consistent across your API.
Example (Adding a Predefined Error to an Endpoint)
import { NodeHttpServer, NodeRuntime } from "@effect/platform-node"
import { Effect, Layer, Schema } from "effect"
import { HttpRouter } from "effect/http"
import { HttpApi, HttpApiBuilder, HttpApiEndpoint, HttpApiError, HttpApiGroup, HttpApiScalar } from "effect/http-api"
import { createServer } from "node:http"
const User = Schema.Struct({
id: Schema.Int,
name: Schema.String
})
const Api = HttpApi.make("MyApi")
.add(
HttpApiGroup.make("Users")
.add(
HttpApiEndpoint.get("getUser", "/user/:id", {
params: {
id: Schema.Int
},
success: User,
error: [
// Add a 404 error JSON response for this endpoint
HttpApiError.NotFound,
// Add a 401 error JSON response for unauthorized access
HttpApiError.Unauthorized
]
})
)
)
const GroupLayer = HttpApiBuilder.group(
Api,
"Users",
(handlers) =>
handlers
.handle("getUser", (ctx) => {
const id = ctx.params.id
if (id === 1) {
return Effect.fail(new HttpApiError.NotFound({}))
}
return Effect.succeed({ id, name: `User ${id}` })
})
)
const ApiLayer = HttpApiBuilder.layer(Api).pipe(
Layer.provide(GroupLayer),
Layer.provide(HttpApiScalar.layer(Api)),
HttpRouter.serve,
Layer.provide(NodeHttpServer.layer(createServer, { port: 3000 }))
)
Layer.launch(ApiLayer).pipe(NodeRuntime.runMain)
| Name | Status | Description |
|---|---|---|
HttpApiDecodeError |
400 | Represents an error where the request did not match the expected schema. Includes detailed issues. |
BadRequest |
400 | Indicates that the request was malformed or invalid. |
Unauthorized |
401 | Indicates that authentication is required but missing or invalid. |
Forbidden |
403 | Indicates that the client does not have permission to access the requested resource. |
NotFound |
404 | Indicates that the requested resource could not be found. |
MethodNotAllowed |
405 | Indicates that the HTTP method used is not allowed for the requested resource. |
NotAcceptable |
406 | Indicates that the requested resource cannot be delivered in a format acceptable to the client. |
RequestTimeout |
408 | Indicates that the server timed out waiting for the client request. |
Conflict |
409 | Indicates a conflict in the request, such as conflicting data. |
Gone |
410 | Indicates that the requested resource is no longer available and will not return. |
InternalServerError |
500 | Indicates an unexpected server error occurred. |
NotImplemented |
501 | Indicates that the requested functionality is not implemented on the server. |
ServiceUnavailable |
503 | Indicates that the server is temporarily unavailable, often due to maintenance or overload. |
Predefined NoContent Error Types
Each predefined error also has a NoContent variant that responds with the status code but no body.
Example (Using a Predefined NoContent Error Type)
import { NodeHttpServer, NodeRuntime } from "@effect/platform-node"
import { Effect, Layer, Schema } from "effect"
import { HttpRouter } from "effect/http"
import { HttpApi, HttpApiBuilder, HttpApiEndpoint, HttpApiError, HttpApiGroup, HttpApiScalar } from "effect/http-api"
import { createServer } from "node:http"
const User = Schema.Struct({
id: Schema.Int,
name: Schema.String
})
const Api = HttpApi.make("MyApi")
.add(
HttpApiGroup.make("Users")
.add(
HttpApiEndpoint.get("getUser", "/user/:id", {
params: {
id: Schema.Int
},
success: User,
error: [
// Add a 404 error no-content response for this endpoint
HttpApiError.NotFoundNoContent,
// Add a 401 error no-content response for unauthorized access
HttpApiError.UnauthorizedNoContent
]
})
)
)
const GroupLayer = HttpApiBuilder.group(
Api,
"Users",
(handlers) =>
handlers
.handle("getUser", (ctx) => {
const id = ctx.params.id
if (id === 1) {
return Effect.fail(new HttpApiError.NotFound({}))
}
return Effect.succeed({ id, name: `User ${id}` })
})
)
const ApiLayer = HttpApiBuilder.layer(Api).pipe(
Layer.provide(GroupLayer),
Layer.provide(HttpApiScalar.layer(Api)),
HttpRouter.serve,
Layer.provide(NodeHttpServer.layer(createServer, { port: 3000 }))
)
Layer.launch(ApiLayer).pipe(NodeRuntime.runMain)
Customizing Schema Error Responses
By default, when a request fails schema validation (e.g., an invalid query parameter or a malformed path parameter), the framework responds with an empty 400 Bad Request. If you want to replace that response with a custom error, use HttpApiMiddleware.layerSchemaErrorTransform.
This function creates a middleware layer that intercepts any SchemaError thrown during request decoding and lets you return your own error instead.
Example (Returning a Custom Error on Validation Failure)
In this example, if a client sends a non-integer id query parameter, the API responds with a 422 status and a JSON body describing the problem, instead of the default empty 400.
import { NodeHttpServer, NodeRuntime } from "@effect/platform-node"
import { Effect, Layer, Schema } from "effect"
import { HttpRouter } from "effect/http"
import {
HttpApi,
HttpApiBuilder,
HttpApiEndpoint,
HttpApiGroup,
HttpApiMiddleware,
HttpApiScalar,
HttpApiSchema
} from "effect/http-api"
import { createServer } from "node:http"
// Define a custom error for validation failures
class ValidationError extends Schema.TaggedError<ValidationError>()(
"ValidationError",
{
message: Schema.String
}
) {}
// Define the middleware service, declaring the error it can produce
class SchemaErrorHandler extends HttpApiMiddleware.Service<SchemaErrorHandler>()(
"api/SchemaErrorHandler",
{
error: ValidationError.pipe(HttpApiSchema.status(422))
}
) {}
// Implement the middleware layer
const SchemaErrorHandlerLayer = HttpApiMiddleware.layerSchemaErrorTransform(
SchemaErrorHandler,
(schemaError) =>
Effect.fail(
new ValidationError({
message: `Invalid request: ${schemaError.message}`
})
)
)
const User = Schema.Struct({
id: Schema.Int,
name: Schema.String
})
const Api = HttpApi.make("MyApi").add(
HttpApiGroup.make("Users").add(
HttpApiEndpoint.get("getUser", "/user", {
query: {
id: Schema.Int
},
success: User
})
// Attach the middleware to this endpoint only
.middleware(SchemaErrorHandler)
)
)
const GroupLayer = HttpApiBuilder.group(
Api,
"Users",
(handlers) => handlers.handle("getUser", (ctx) => Effect.succeed({ id: ctx.query.id, name: `User ${ctx.query.id}` }))
)
const ApiLayer = HttpApiBuilder.layer(Api).pipe(
Layer.provide(GroupLayer),
Layer.provide(SchemaErrorHandlerLayer),
Layer.provide(HttpApiScalar.layer(Api)),
HttpRouter.serve,
Layer.provide(NodeHttpServer.layer(createServer, { port: 3000 }))
)
Layer.launch(ApiLayer).pipe(NodeRuntime.runMain)
// Test:
// curl "http://localhost:3000/user?id=1" # 200 OK
// curl "http://localhost:3000/user?id=abc" # 422 with ValidationError JSON
The middleware can be attached at different scopes:
- Endpoint:
.middleware(SchemaErrorHandler)on a single endpoint (as shown above). - Group:
.middleware(SchemaErrorHandler)on a group to cover all its endpoints. - API:
.middleware(SchemaErrorHandler)on the API to cover every endpoint.
Middlewares
Middleware lets you run shared logic — like logging or authentication — before (or around) your handlers. Define a middleware as a class extending HttpApiMiddleware.Service, implement it as a Layer, and attach it to an endpoint, a group, or the entire API.
Example (Defining a Logger Middleware)
import { NodeHttpServer, NodeRuntime } from "@effect/platform-node"
import { Effect, Layer, Schema } from "effect"
import { HttpRouter, HttpServerRequest } from "effect/http"
import {
HttpApi,
HttpApiBuilder,
HttpApiEndpoint,
HttpApiGroup,
HttpApiMiddleware,
HttpApiScalar,
HttpApiSchema
} from "effect/http-api"
import { createServer } from "node:http"
class Logger extends HttpApiMiddleware.Service<Logger>()("Http/Logger", {
// default is 500 Internal Server Error with JSON encoding
error: Schema.String
.pipe(
HttpApiSchema.status(405), // override default status code
HttpApiSchema.asText() // override default encoding
)
}) {}
const User = Schema.Struct({
id: Schema.Finite,
name: Schema.String
})
const Api = HttpApi.make("api").add(
HttpApiGroup.make("group").add(
HttpApiEndpoint.get("getUser", "/user/:id", {
params: {
id: Schema.Int
},
success: User
})
// Apply the middleware to a single endpoint
.middleware(Logger)
)
// Or apply the middleware to the entire group
.middleware(Logger)
)
const GroupLayer = HttpApiBuilder.group(
Api,
"group",
(handlers) =>
handlers.handle("getUser", (ctx) => {
const id = ctx.params.id
return Effect.succeed({ id, name: `User ${id}` })
})
)
const LoggerLayer = Layer.effect(
Logger,
Effect.gen(function*() {
yield* Effect.log("creating Logger middleware")
return (res) =>
Effect.gen(function*() {
const request = yield* HttpServerRequest.HttpServerRequest
yield* Effect.log(`Request: ${request.method} ${request.url}`)
return yield* res
})
})
)
const ApiLayer = HttpApiBuilder.layer(Api).pipe(
Layer.provide(GroupLayer),
Layer.provide(HttpApiScalar.layer(Api)),
Layer.provide(LoggerLayer),
HttpRouter.serve,
Layer.provide(NodeHttpServer.layer(createServer, { port: 3000 }))
)
Layer.launch(ApiLayer).pipe(NodeRuntime.runMain)
// Test this with this curl command:
// curl "http://localhost:3000/user/1"
Interdependent Middleware
Middleware can depend on services provided by other middleware. Declare the dependency with requires and declare the produced service with provides.
When you attach interdependent middleware to an endpoint, group, or API, the middleware that uses requires must come BEFORE the middleware that provides that service. The earlier middleware wraps the later middleware, so it can consume the service that the later middleware adds to the request effect.
Example (Middleware that consumes another middleware's output)
import { Context, Effect, Layer, Schema } from "effect"
import { HttpApi, HttpApiEndpoint, HttpApiGroup, HttpApiMiddleware } from "effect/http-api"
class AuthInfo extends Context.Service<AuthInfo, {
readonly userId: string
}>()("AuthInfo") {}
class LoadAuth extends HttpApiMiddleware.Service<LoadAuth, {
readonly provides: AuthInfo
}>()("LoadAuth") {}
class RequireAuth extends HttpApiMiddleware.Service<RequireAuth, {
readonly requires: AuthInfo
}>()("RequireAuth") {}
const Api = HttpApi.make("api").add(
HttpApiGroup.make("users").add(
HttpApiEndpoint.get("me", "/me", {
success: Schema.String
})
// RequireAuth reads AuthInfo, so it must appear first.
.middleware(RequireAuth)
// LoadAuth provides AuthInfo to middleware that appears before it.
.middleware(LoadAuth)
)
)
const LoadAuthLayer = Layer.effect(
LoadAuth,
Effect.succeed((effect) =>
Effect.provideService(effect, AuthInfo, {
userId: "user-1"
})
)
)
const RequireAuthLayer = Layer.effect(
RequireAuth,
Effect.succeed(
Effect.fnUntraced(function*(effect) {
const authInfo = yield* AuthInfo
yield* Effect.log(`authenticated user ${authInfo.userId}`)
return yield* effect
})
)
)
Security
The HttpApiSecurity module lets you declare how an endpoint is protected. These declarations show up in the generated OpenAPI spec and are enforced at runtime through middleware.
Supported authorization types:
| Authorization Type | Description |
|---|---|
HttpApiSecurity.apiKey |
API key authorization via headers, query parameters, or cookies. |
HttpApiSecurity.basic |
HTTP Basic authentication. |
HttpApiSecurity.bearer |
Bearer token authentication. |
Attach a security scheme to an endpoint, group, or the entire API via HttpApiMiddleware.
Example (Defining Security Middleware)
import { Context, Schema } from "effect"
import { HttpApi, HttpApiEndpoint, HttpApiGroup, HttpApiMiddleware, HttpApiSecurity } from "effect/http-api"
// Define a schema for the "User"
class User extends Schema.Class<User>("User")({ id: Schema.Finite }) {}
// Define a schema for the "Unauthorized" error
class Unauthorized extends Schema.TaggedError<Unauthorized>()(
"Unauthorized",
{},
// Specify the HTTP status code for unauthorized errors
{ httpApiStatus: 401 }
) {}
// Define a Context.Tag for the authenticated user
class CurrentUser extends Context.Service<CurrentUser, User>()("CurrentUser") {}
// Create the Authorization middleware
class Authorization extends HttpApiMiddleware.Service<Authorization, {
// Specify the resource this middleware will provide
provides: CurrentUser
}>()(
"Authorization",
{
// Define the error schema for unauthorized access
error: Unauthorized,
// Add security definitions
security: {
// ┌─── Custom name for the security definition
// ▼
myBearer: HttpApiSecurity.bearer
// Additional security definitions can be added here.
// They will attempt to be resolved in the order they are defined.
}
}
) {}
const api = HttpApi.make("api")
.add(
HttpApiGroup.make("group")
.add(
HttpApiEndpoint.get("get", "/", {
success: Schema.String
})
// Apply the middleware to a single endpoint
.middleware(Authorization)
)
// Or apply the middleware to the entire group
.middleware(Authorization)
)
// Or apply the middleware to the entire API
.middleware(Authorization)
Implementing HttpApiSecurity middleware
To enforce a security scheme, implement its middleware as a Layer. The layer returns an object with a handler for each security definition. Each handler receives the credential (e.g., a Bearer token as a Redacted value) and must return the resource the middleware provides (e.g., the current user).
Example (Implementing Bearer Token Authentication Middleware)
import { Context, Effect, Layer, Redacted, Schema } from "effect"
import { HttpApiMiddleware, HttpApiSecurity } from "effect/http-api"
class User extends Schema.Class<User>("User")({ id: Schema.Finite }) {}
class Unauthorized extends Schema.TaggedError<Unauthorized>()(
"Unauthorized",
{},
// Specify the HTTP status code for unauthorized errors
{ httpApiStatus: 401 }
) {}
class CurrentUser extends Context.Service<CurrentUser, User>()("CurrentUser") {}
class Authorization extends HttpApiMiddleware.Service<Authorization, {
provides: CurrentUser
}>()(
"Authorization",
{
error: Unauthorized,
security: {
myBearer: HttpApiSecurity.bearer
}
}
) {}
const AuthorizationLayer = Layer.succeed(
Authorization,
// Return the security handlers for the middleware
{
// Define the handler for the Bearer token
// The Bearer token is redacted for security
myBearer: (effect, opts) =>
Effect.provideServiceEffect(
effect,
CurrentUser,
Effect.gen(function*() {
yield* Effect.log(
"checking bearer token",
Redacted.value(opts.credential)
)
// Return a mock User object as the CurrentUser
return new User({ id: 1 })
})
)
}
)
Adding Descriptions to Security Definitions
Use HttpApiSecurity.annotate to attach metadata — like a description — to a security definition. This metadata appears in the generated docs.
Example (Adding a Description to a Bearer Token Security Definition)
import { Context, Schema } from "effect"
import { HttpApiMiddleware, HttpApiSecurity, OpenApi } from "effect/http-api"
class User extends Schema.Class<User>("User")({ id: Schema.Finite }) {}
class Unauthorized extends Schema.TaggedError<Unauthorized>()(
"Unauthorized",
{},
// Specify the HTTP status code for unauthorized errors
{ httpApiStatus: 401 }
) {}
class CurrentUser extends Context.Service<CurrentUser, User>()("CurrentUser") {}
class Authorization extends HttpApiMiddleware.Service<Authorization, {
provides: CurrentUser
}>()(
"Authorization",
{
error: Unauthorized,
security: {
myBearer: HttpApiSecurity.bearer.pipe(
// Add a description to the security definition
HttpApiSecurity.annotate(OpenApi.Description, "my description")
)
}
}
) {}
Setting HttpApiSecurity cookies
Use HttpApiBuilder.securitySetCookie to set a security cookie from a handler. The cookie is created with HttpOnly and Secure flags by default.
Example (Setting a Security Cookie in a Login Handler)
import { Redacted, Schema } from "effect"
import { HttpApi, HttpApiBuilder, HttpApiEndpoint, HttpApiGroup, HttpApiSecurity } from "effect/http-api"
const Api = HttpApi.make("MyApi")
.add(
HttpApiGroup.make("Users")
.add(
HttpApiEndpoint.get("login", "/login", {
params: {
success: Schema.String
}
})
)
)
// Define the security configuration for an API key stored in a cookie
const security = HttpApiSecurity.apiKey({
// Specify that the API key is stored in a cookie
in: "cookie",
// Define the cookie name,
key: "token"
})
const UsersApiLayer = HttpApiBuilder.group(Api, "Users", (handlers) =>
handlers.handle("login", () =>
// Set the security cookie with a redacted value
HttpApiBuilder.securitySetCookie(security, Redacted.make("keep me secret"))))
Using Services Inside a HttpApiEndpoint
Handlers can access any Effect service. Because HttpApiBuilder.group returns an Effect, you can yield* services directly inside your handler logic.
Example (Using Services in a Endpoint Implementation)
import { NodeHttpServer, NodeRuntime } from "@effect/platform-node"
import { Context, Effect, Layer, Schema } from "effect"
import { HttpRouter } from "effect/http"
import { HttpApi, HttpApiBuilder, HttpApiEndpoint, HttpApiGroup, HttpApiScalar } from "effect/http-api"
import { createServer } from "node:http"
const User = Schema.Struct({
id: Schema.Int,
name: Schema.String
})
// Define the UsersRepository service
class UsersRepository extends Context.Service<UsersRepository, {
readonly findById: (id: number) => Effect.Effect<typeof User.Type>
}>()("UsersRepository") {}
const Api = HttpApi.make("MyApi")
.add(
HttpApiGroup.make("Users")
.add(
HttpApiEndpoint.get("getUser", "/user/:id", {
params: {
id: Schema.Int
},
success: User
})
)
)
const GroupLayer = HttpApiBuilder.group(
Api,
"Users",
(handlers) =>
handlers
.handle("getUser", (ctx) => {
const id = ctx.params.id
return Effect.gen(function*() {
// Access the UsersRepository service
const repository = yield* UsersRepository
return yield* repository.findById(id)
})
})
)
const ApiLayer = HttpApiBuilder.layer(Api).pipe(
Layer.provide(GroupLayer),
Layer.provide(HttpApiScalar.layer(Api)),
Layer.provide(
Layer.succeed(UsersRepository, {
findById: (id) => Effect.succeed({ id, name: `User ${id}` })
})
),
HttpRouter.serve,
Layer.provide(NodeHttpServer.layer(createServer, { port: 3000 }))
)
Layer.launch(ApiLayer).pipe(NodeRuntime.runMain)
OpenAPI Documentation
Add interactive API documentation with HttpApiScalar (Scalar UI) or HttpApiSwagger (Swagger UI). Both read your API definition and generate a browsable docs page at /docs.
Example (Adding Scalar Documentation to an API)
import { NodeHttpServer, NodeRuntime } from "@effect/platform-node"
import { Effect, Layer, Schema } from "effect"
import { HttpRouter } from "effect/http"
import { HttpApi, HttpApiBuilder, HttpApiEndpoint, HttpApiGroup, HttpApiScalar } from "effect/http-api"
import { createServer } from "node:http"
const User = Schema.Struct({
id: Schema.Int,
name: Schema.String
})
const IdParam = Schema.Int
const Api = HttpApi.make("MyApi")
.add(
HttpApiGroup.make("Users")
.add(
HttpApiEndpoint.get("getUsers", "/users", {
success: Schema.Array(User)
}),
HttpApiEndpoint.get("getUser", "/user/:id", {
params: {
id: IdParam
},
success: User
}),
HttpApiEndpoint.post("createUser", "/user", {
payload: User,
success: User
}),
HttpApiEndpoint.delete("deleteUser", "/user/:id", {
params: {
id: IdParam
}
}),
HttpApiEndpoint.patch("updateUser", "/user/:id", {
params: {
id: IdParam
},
// Specify the schema for the request payload
payload: Schema.Struct({
name: Schema.String // Only the name can be updated
}),
// Specify the schema for a successful response
success: User
})
)
)
const GroupLayer = HttpApiBuilder.group(
Api,
"Users",
(handlers) =>
handlers.handleAll({
getUsers: () =>
Effect.succeed(
[{ id: 1, name: "User 1" }, { id: 2, name: "User 2" }]
),
getUser: (ctx) => {
const id = ctx.params.id
return Effect.succeed({ id, name: `User ${id}` })
},
createUser: (ctx) => {
const user = ctx.payload
return Effect.succeed(user)
},
deleteUser: (ctx) => {
const id = ctx.params.id
return Effect.log(`Deleting user ${id}`)
},
updateUser: (ctx) => {
const id = ctx.params.id
return Effect.succeed({ id, name: `User ${id}` })
}
})
)
const ApiLayer = HttpApiBuilder.layer(Api).pipe(
Layer.provide(GroupLayer),
Layer.provide(HttpApiScalar.layer(Api)), // "/docs" is the default path.
HttpRouter.serve,
Layer.provide(NodeHttpServer.layer(createServer, { port: 3000 }))
)
Layer.launch(ApiLayer).pipe(NodeRuntime.runMain)
After running the server, open your browser and navigate to http://localhost:3000/docs.
This URL will display the Scalar documentation, allowing you to explore the API's endpoints, request parameters, and response structures interactively.
Adding OpenAPI Annotations
Annotations let you enrich the generated OpenAPI spec with titles, descriptions, server URLs, and more. They are added via the .annotate method on HttpApi, HttpApiGroup, or HttpApiEndpoint.
HttpApi
Below is a list of available annotations for a top-level HttpApi. They can be added using the .annotate method:
| Annotation | Description |
|---|---|
HttpApi.AdditionalSchemas |
Adds custom schemas to the final OpenAPI specification. Only schemas with an identifier annotation are included. |
OpenApi.Description |
Sets a general description for the API. |
OpenApi.Title |
Sets the title of the API. |
OpenApi.Version |
Sets the version of the API. |
OpenApi.License |
Defines the license used by the API. |
OpenApi.Summary |
Provides a brief summary of the API. |
OpenApi.Servers |
Lists server URLs and optional metadata such as variables. |
OpenApi.Override |
Merges the supplied fields into the resulting specification. |
OpenApi.Transform |
Allows you to modify the final specification with a custom function. |
Example (Annotating the Top-Level API)
import { Schema } from "effect"
import { HttpApi, OpenApi } from "effect/http-api"
const api = HttpApi.make("api")
// Provide additional schemas
.annotate(HttpApi.AdditionalSchemas, [
Schema.String.annotate({ identifier: "MyString" })
])
// Add a description
.annotate(OpenApi.Description, "my description")
// Set license information
.annotate(OpenApi.License, { name: "MIT", url: "http://example.com" })
// Provide a summary
.annotate(OpenApi.Summary, "my summary")
// Define servers
.annotate(OpenApi.Servers, [
{
url: "http://example.com",
description: "example",
variables: { a: { default: "b", enum: ["c"], description: "d" } }
}
])
// Override parts of the generated specification
.annotate(OpenApi.Override, {
tags: [{ name: "a", description: "a-description" }]
})
// Apply a transform function to the final specification
.annotate(OpenApi.Transform, (spec) => ({
...spec,
tags: [...spec.tags, { name: "b", description: "b-description" }]
}))
// Generate the OpenAPI specification from the annotated API
const spec = OpenApi.fromApi(api)
console.log(JSON.stringify(spec, null, 2))
/*
Output:
{
"openapi": "3.1.0",
"info": {
"title": "Api",
"version": "0.0.1",
"description": "my description",
"license": {
"name": "MIT",
"url": "http://example.com"
},
"summary": "my summary"
},
"paths": {},
"components": {
"schemas": {
"MyString": {
"type": "string"
}
},
"securitySchemes": {}
},
"security": [],
"tags": [
{
"name": "a",
"description": "a-description"
},
{
"name": "b",
"description": "b-description"
}
],
"servers": [
{
"url": "http://example.com",
"description": "example",
"variables": {
"a": {
"default": "b",
"enum": [
"c"
],
"description": "d"
}
}
}
]
}
*/
HttpApiGroup
The following annotations can be added to an HttpApiGroup:
| Annotation | Description |
|---|---|
OpenApi.Description |
Sets a description for this group. |
OpenApi.ExternalDocs |
Provides external documentation links for the group. |
OpenApi.Override |
Merges specified fields into the resulting specification. |
OpenApi.Transform |
Lets you modify the final group specification with a custom function. |
OpenApi.Exclude |
Excludes the group from the final OpenAPI specification. |
Example (Annotating a Group)
import { HttpApi, HttpApiGroup, OpenApi } from "effect/http-api"
const api = HttpApi.make("api")
.add(
HttpApiGroup.make("group")
// Add a description for the group
.annotate(OpenApi.Description, "my description")
// Provide external documentation links
.annotate(OpenApi.ExternalDocs, {
url: "http://example.com",
description: "example"
})
// Override parts of the final output
.annotate(OpenApi.Override, { name: "my name" })
// Transform the final specification for this group
.annotate(OpenApi.Transform, (spec) => ({
...spec,
name: spec.name + "-transformed"
}))
)
.add(
HttpApiGroup.make("excluded")
// Exclude the group from the final specification
.annotate(OpenApi.Exclude, true)
)
// Generate the OpenAPI spec
const spec = OpenApi.fromApi(api)
console.log(JSON.stringify(spec, null, 2))
/*
Output:
{
"openapi": "3.1.0",
"info": {
"title": "Api",
"version": "0.0.1"
},
"paths": {},
"components": {
"schemas": {},
"securitySchemes": {}
},
"security": [],
"tags": [
{
"name": "my name-transformed",
"description": "my description",
"externalDocs": {
"url": "http://example.com",
"description": "example"
}
}
]
}
*/
HttpApiEndpoint
For an HttpApiEndpoint, you can use the following annotations:
| Annotation | Description |
|---|---|
OpenApi.Description |
Adds a description for this endpoint. |
OpenApi.Summary |
Provides a short summary of the endpoint's purpose. |
OpenApi.Deprecated |
Marks the endpoint as deprecated. |
OpenApi.ExternalDocs |
Supplies external documentation links for the endpoint. |
OpenApi.Override |
Merges specified fields into the resulting specification for this endpoint. |
OpenApi.Transform |
Lets you modify the final endpoint specification with a custom function. |
OpenApi.Exclude |
Excludes the endpoint from the final OpenAPI specification. |
Example (Annotating an Endpoint)
import { Schema } from "effect"
import { HttpApi, HttpApiEndpoint, HttpApiGroup, OpenApi } from "effect/http-api"
const api = HttpApi.make("api").add(
HttpApiGroup.make("group")
.add(
HttpApiEndpoint.get("get", "/", {
success: Schema.String
})
// Add a description
.annotate(OpenApi.Description, "my description")
// Provide a summary
.annotate(OpenApi.Summary, "my summary")
// Mark the endpoint as deprecated
.annotate(OpenApi.Deprecated, true)
// Provide external documentation
.annotate(OpenApi.ExternalDocs, {
url: "http://example.com",
description: "example"
})
)
.add(
HttpApiEndpoint.get("excluded", "/excluded", {
success: Schema.String
})
// Exclude this endpoint from the final specification
.annotate(OpenApi.Exclude, true)
)
)
// Generate the OpenAPI spec
const spec = OpenApi.fromApi(api)
console.log(JSON.stringify(spec, null, 2))
/*
Output:
{
"openapi": "3.1.0",
"info": {
"title": "Api",
"version": "0.0.1"
},
"paths": {
"/": {
"get": {
"tags": [
"group"
],
"operationId": "group.get",
"parameters": [],
"security": [],
"responses": {
"200": {
"description": "Success",
"content": {
"application/json": {
"schema": {
"$ref": "#/components/schemas/String_"
}
}
}
},
"400": {
"description": "The request or response did not match the expected schema",
"content": {
"application/json": {
"schema": {
"type": "object",
"properties": {
"_tag": {
"type": "string",
"enum": [
"HttpApiSchemaError"
]
},
"message": {
"$ref": "#/components/schemas/String_"
}
},
"required": [
"_tag",
"message"
],
"additionalProperties": false
}
}
}
}
},
"description": "my description",
"summary": "my summary",
"deprecated": true,
"externalDocs": {
"url": "http://example.com",
"description": "example"
}
}
}
},
"components": {
"schemas": {
"String_": {
"type": "string"
}
},
"securitySchemes": {}
},
"security": [],
"tags": [
{
"name": "group"
}
]
}
*/
The default response description is "Success". You can override this by annotating the schema.
Example (Defining a custom response description)
import { Schema } from "effect"
import { HttpApi, HttpApiEndpoint, HttpApiGroup, OpenApi } from "effect/http-api"
const User = Schema.Struct({
id: Schema.Finite,
name: Schema.String
}).annotate({ identifier: "User" })
const api = HttpApi.make("api").add(
HttpApiGroup.make("group").add(
HttpApiEndpoint.get("getUsers", "/users", {
success: Schema.Array(User).annotate({
description: "Returns an array of users"
})
})
)
)
const spec = OpenApi.fromApi(api)
console.log(JSON.stringify(spec.paths, null, 2))
/*
Output:
{
"/users": {
"get": {
"tags": [
"group"
],
"operationId": "group.getUsers",
"parameters": [],
"security": [],
"responses": {
"200": {
"description": "Returns an array of users",
"content": {
"application/json": {
"schema": {
"type": "array",
"items": {
"type": "object",
"properties": {
"id": {
"type": "number"
},
"name": {
"$ref": "#/components/schemas/String_"
}
},
"required": [
"id",
"name"
],
"additionalProperties": false
},
"description": "Returns an array of users"
}
}
}
},
"400": {
"description": "The request or response did not match the expected schema",
"content": {
"application/json": {
"schema": {
"type": "object",
"properties": {
"_tag": {
"type": "string",
"enum": [
"HttpApiSchemaError"
]
},
"message": {
"$ref": "#/components/schemas/String_"
}
},
"required": [
"_tag",
"message"
],
"additionalProperties": false
}
}
}
}
}
}
}
}
*/
Top Level Groups
When a group is topLevel, its name is not prepended to operation IDs in the OpenAPI spec. Use this when the group is just for tagging and you want shorter, cleaner operation IDs.
Example (Using a Top-Level Group)
import { Schema } from "effect"
import { HttpApi, HttpApiEndpoint, HttpApiGroup, OpenApi } from "effect/http-api"
const api = HttpApi.make("api").add(
// Mark the group as top-level
HttpApiGroup.make("group", { topLevel: true }).add(
HttpApiEndpoint.get("get", "/", {
success: Schema.String
})
)
)
// Generate the OpenAPI spec
const spec = OpenApi.fromApi(api)
console.log(JSON.stringify(spec.paths, null, 2))
/*
Output:
{
"/": {
"get": { // The operation ID is not prefixed with "group"
"tags": [
"group"
],
"operationId": "get",
"parameters": [],
"security": [],
"responses": {
"200": {
"description": "Success",
"content": {
"application/json": {
"schema": {
"$ref": "#/components/schemas/String_"
}
}
}
},
"400": {
"description": "The request or response did not match the expected schema",
"content": {
"application/json": {
"schema": {
"type": "object",
"properties": {
"_tag": {
"type": "string",
"enum": [
"HttpApiSchemaError"
]
},
"message": {
"$ref": "#/components/schemas/String_"
}
},
"required": [
"_tag",
"message"
],
"additionalProperties": false
}
}
}
}
}
}
}
}
*/
Deriving a Client
The HttpApiClient module generates a fully typed client from your API definition. Each endpoint becomes a method — grouped by HttpApiGroup name — so calling your API is as simple as calling a function.
Example (Deriving and Using a Client)
import { NodeHttpServer, NodeRuntime } from "@effect/platform-node"
import { Effect, Layer, Schema } from "effect"
import { HttpRouter } from "effect/http"
import { FetchHttpClient } from "effect/http"
import { HttpApi, HttpApiBuilder, HttpApiClient, HttpApiEndpoint, HttpApiGroup } from "effect/http-api"
import { createServer } from "node:http"
const Api = HttpApi.make("MyApi")
.add(
HttpApiGroup.make("Greetings")
.add(
HttpApiEndpoint.get("hello", "/", {
success: Schema.String
})
)
)
const GroupLayer = HttpApiBuilder.group(
Api,
"Greetings",
(handlers) => handlers.handle("hello", () => Effect.succeed("Hello, World!"))
)
const ApiLayer = HttpApiBuilder.layer(Api).pipe(
Layer.provide(GroupLayer),
HttpRouter.serve,
Layer.provide(NodeHttpServer.layer(createServer, { port: 3000 }))
)
Layer.launch(ApiLayer).pipe(NodeRuntime.runMain)
// Create a program that derives and uses the client
const program = Effect.gen(function*() {
// Derive the client
const client = yield* HttpApiClient.make(Api, {
baseUrl: "http://localhost:3000"
})
// Call the "hello-world" endpoint
const hello = yield* client.Greetings.hello()
console.log(hello)
})
// Provide a Fetch-based HTTP client and run the program
Effect.runFork(program.pipe(Effect.provide(FetchHttpClient.layer)))
/*
Output:
[18:55:26.051] INFO (#2): Listening on http://0.0.0.0:3000
[18:55:26.057] INFO (#12) http.span=2ms: Sent HTTP response { 'http.method': 'GET', 'http.url': '/', 'http.status': 200 }
Hello, World!
*/
Top Level Groups
When a group is topLevel, its endpoints are exposed as top-level methods on the client instead of being nested under the group name.
Example (Using a Top-Level Group in the Client)
import { NodeHttpServer, NodeRuntime } from "@effect/platform-node"
import { Effect, Layer, Schema } from "effect"
import { HttpRouter } from "effect/http"
import { FetchHttpClient } from "effect/http"
import { HttpApi, HttpApiBuilder, HttpApiClient, HttpApiEndpoint, HttpApiGroup } from "effect/http-api"
import { createServer } from "node:http"
const Api = HttpApi.make("MyApi")
.add(
HttpApiGroup.make("Greetings", { topLevel: true })
.add(
HttpApiEndpoint.get("hello", "/", {
success: Schema.String
})
)
)
const GroupLayer = HttpApiBuilder.group(
Api,
"Greetings",
(handlers) => handlers.handle("hello", () => Effect.succeed("Hello, World!"))
)
const ApiLayer = HttpApiBuilder.layer(Api).pipe(
Layer.provide(GroupLayer),
HttpRouter.serve,
Layer.provide(NodeHttpServer.layer(createServer, { port: 3000 }))
)
Layer.launch(ApiLayer).pipe(NodeRuntime.runMain)
const program = Effect.gen(function*() {
const client = yield* HttpApiClient.make(Api, {
baseUrl: "http://localhost:3000"
})
// The `hello` method is not nested under the "group" name
const hello = yield* client.hello()
console.log(hello)
})
Effect.runFork(program.pipe(Effect.provide(FetchHttpClient.layer)))
Converting to a Web Handler
If you need to plug your API into an existing HTTP server (instead of using NodeHttpServer), convert it to a standard web handler with HttpApiBuilder.toWebHandler. The returned handler function takes a Request and returns a Response.
Example (Creating and Serving a Web Handler)
import { Effect, Layer, Schema } from "effect"
import { HttpRouter, HttpServer } from "effect/http"
import { HttpApi, HttpApiBuilder, HttpApiEndpoint, HttpApiGroup, HttpApiScalar } from "effect/http-api"
import * as http from "node:http"
const Api = HttpApi.make("myApi").add(
HttpApiGroup.make("group").add(
HttpApiEndpoint.get("get", "/", {
success: Schema.String
})
)
)
const GroupLayer = HttpApiBuilder.group(
Api,
"group",
(handlers) => handlers.handle("get", () => Effect.succeed("Hello, world!"))
)
const ApiLayer = HttpApiBuilder.layer(Api).pipe(
Layer.provide(GroupLayer),
Layer.provide(HttpApiScalar.layer(Api)),
Layer.provide(HttpServer.layerServices)
)
// Convert the API to a web handler
const { dispose, handler } = HttpRouter.toWebHandler(
Layer.mergeAll(ApiLayer)
)
// Serving the handler using a custom HTTP server
http
.createServer(async (req, res) => {
const url = `http://${req.headers.host}${req.url}`
const init: RequestInit = {
method: req.method!
}
const response = await handler(new Request(url, init))
res.writeHead(
response.status,
response.statusText,
Object.fromEntries(response.headers.entries())
)
const responseBody = await response.arrayBuffer()
res.end(Buffer.from(responseBody))
})
.listen(3000, () => {
console.log("Server running at http://localhost:3000/")
})
.on("close", () => {
dispose()
})