trpc-swagger

---

Swagger intigration for tRPC

• Easy REST endpoints for your tRPC procedures.
• Perfect for incremental adoption.
• OpenAPI version 3.0.3.

Fork Notice

The original repo trpc-openapi no longer appears to be maintained. The goal of this fork is to add more control for error responses, support more frameworks, and support the new procedure types in @trpc v11.x.x. PRs Are welcome

Local Examples

If you've pulled the repo. you can run any of the example projects by first running these 2 commands:

yarn install

yarn build

Then select a workspace

yarn workspace with-[WORKSPACE_NAME] run dev

Ergo

yarn workspace with-nextjs-app run dev
yarn workspace with-nextjs-app run build

Usage

1. Install trpc-swagger

npm install trpc-swagger --save

yarn add trpc-swagger

pnpm add trpc-swagger

bun add trpc-swagger

2. Add OpenApiMeta to your tRPC instance

// @/server/trpc.ts
import { initTRPC } from '@trpc/server'
import { OpenApiMeta } from 'trpc-swagger'

// VERC: This
const t = initTRPC.create()

// VERC: Becomes
const t = initTRPC.meta<OpenApiMeta>().create()

// VERC: Advanced create configs
const t = initTRPC.meta<OpenApiMeta>().create({ ... })

3. Enable openapi support for a procedure.

// @/server/index.ts
export const appRouter = t.router({
  sayHello: t.procedure
    .meta({ 
      openapi: { method: 'GET', path: '/say-hello' } 
    })
    .input(z.object({ 
      name: z.string() 
    }))
    .output(z.object({ 
      greeting: z.string() 
    }))
    .query(({ input }) => {
      return { greeting: `Hello ${input.name}!` }
    })
})

4. Generate an OpenAPI document.

// @/server/swagger.ts
import { generateOpenApiDocument } from 'trpc-swagger'
import { appRouter } from './appRouter'

/* 👇 */
export const openApiDocument = generateOpenApiDocument(appRouter, {
  title: 'tRPC Swagger',
  version: '1.0.0', // consider making this pull version from package.json
  baseUrl: 'http://localhost:3000', // consider making this dynamic
  docsUrl: "https://github.com/vercjames/package-trpc-swagger",
  tags: ["tag1", "tag2", "tag3", "posts"],
})

5. Add an trpc-swagger handler to your app.

We currently support adapters for Express, Next.js, Next.js 14, Serverless, Fastify, Nuxt & Node:HTTP.

import http from 'http'
import { createOpenApiHttpHandler } from 'trpc-swagger'

import { appRouter } from '../appRouter'

const server = http.createServer(createOpenApiHttpHandler({ router: appRouter })) /* 👈 */

server.listen(3000)

6. Profit 🤑

// client.ts
const res = await fetch('http://localhost:3000/say-hello?name=Verc', { method: 'GET' })
const body = await res.json() /* { greeting: 'Hello Verc!' } */

Requirements

Peer dependencies

Your application requires these 2 packages installed

• tRPC Server v110 (@trpc/server) must be installed.
• Zod v3 (zod@^3.14.4) must be installed (recommended ^3.20.0).

Procedure support

For a procedure to support OpenAPI the following must be true:

• Both input and output parsers are present AND use Zod validation.
• Query input parsers extend Object<{ [string]: String | Number | BigInt | Date }> or Void.
• Mutation input parsers extend Object<{ [string]: AnyType }> or Void.
• meta.openapi.method is GET, POST, PATCH, PUT or DELETE.
• meta.openapi.path is a string starting with /.
• meta.openapi.path parameters exist in input parser as String | Number | BigInt | Date

Please note:

• Data transformers (such as superjson) are ignored.
• Trailing slashes are ignored.
• Routing is case-insensitive.

HTTP Requests

Procedures with a GET/DELETE method will accept inputs via URL query parameters. Procedures with a POST/PATCH/PUT method will accept inputs via the request body with a application/json or application/x-www-form-urlencoded content type.

Path parameters

A procedure can accept a set of inputs via URL path parameters. You can add a path parameter to any OpenAPI procedure by using curly brackets around an input name as a path segment in the meta.openapi.path field.

Query parameters

Query & path parameter inputs are always accepted as a string. This library will attempt to coerce your input values to the following primitive types out of the box: number, boolean, bigint and date. If you wish to support others such as object, array etc. please use z.preprocess().

// Router
export const appRouter = t.router({
  sayHello: t.procedure
    .meta({ openapi: { method: 'GET', path: '/say-hello/{name}' /* 👈 */ } })
    .input(z.object({ name: z.string() /* 👈 */, greeting: z.string() }))
    .output(z.object({ greeting: z.string() }))
    .query(({ input }) => {
      return { greeting: `${input.greeting} ${input.name}!` }
    })
})

// Client
const res = await fetch('http://localhost:3000/say-hello/Verc?greeting=Hello' /* 👈 */, {
  method: 'GET',
})
const body = await res.json() /* { greeting: 'Hello Verc!' } */

Request body

// Router
export const appRouter = t.router({
  sayHello: t.procedure
    .meta({ openapi: { method: 'POST', path: '/say-hello/{name}' /* 👈 */ } })
    .input(z.object({ name: z.string() /* 👈 */, greeting: z.string() }))
    .output(z.object({ greeting: z.string() }))
    .mutation(({ input }) => {
      return { greeting: `${input.greeting} ${input.name}!` }
    })
})

// Client
const res = await fetch('http://localhost:3000/say-hello/Verc' /* 👈 */, {
  method: 'POST',
  headers: { 'Content-Type': 'application/json' },
  body: JSON.stringify({ greeting: 'Hello' }),
})
const body = await res.json() /* { greeting: 'Hello Verc!' } */

Custom headers

Any custom headers can be specified in the meta.openapi.headers array, these headers will not be validated on request. Please consider using Authorization for first-class OpenAPI auth/security support.

HTTP Responses

Status codes will be 200 by default for any successful requests. In the case of an error, the status code will be derived from the thrown TRPCError or fallback to 500.

You can modify the status code or headers for any response using the responseMeta function. Extra responses can be documented in the meta.openapi.extraResponses field.

// Router
export const appRouter = t.router({
  sayHello: t.procedure
    .meta({ openapi: {
      method: 'POST',
      path: '/say-hello/{name}',
      extraResponses: {
          400: {
            description: 'Bad request',
            content: z.object({ reason: z.string().describe("The reason") }),
          },
      }
    }})
    .input(z.object({ name: z.string(), greeting: z.string() }))
    .output(z.object({ greeting: z.string() }))
    .mutation(({ input }) => {
      return { greeting: `${input.greeting} ${input.name}!` }
    })
})

Please see error status codes here.

Authorization

To create protected endpoints, add protect: true to the meta.openapi object of each tRPC procedure. By default, you can then authenticate each request with the createContext function using the Authorization header with the Bearer scheme. If you wish to authenticate requests using a different/additional methods (such as custom headers, or cookies) this can be overwritten by specifying securitySchemes object.

Explore a complete example here.

Server

import { TRPCError, initTRPC } from '@trpc/server'
import { OpenApiMeta } from 'trpc-swagger'

type User = { id: string, name: string }

const users: User[] = [
  {
    id: 'usr_123',
    name: 'Verc',
  },
]

export type Context = { user: User | null }

export const createContext = async ({ req, res }): Promise<Context> => {
  let user: User | null = null
  if (req.headers.authorization) {
    const userId = req.headers.authorization.split(' ')[1]
    user = users.find((_user) => _user.id === userId)
  }
  return { user }
}

const t = initTRPC.context<Context>().meta<OpenApiMeta>().create()

export const appRouter = t.router({
  sayHello: t.procedure
    .meta({ openapi: { method: 'GET', path: '/say-hello', protect: true /* 👈 */ } })
    .input(z.void()) // no input expected
    .output(z.object({ greeting: z.string() }))
    .query(({ input, ctx }) => {
      if (!ctx.user) {
        throw new TRPCError({ message: 'User not found', code: 'UNAUTHORIZED' })
      }
      return { greeting: `Hello ${ctx.user.name}!` }
    }),
})

Client

const res = await fetch('http://localhost:3000/say-hello', {
  method: 'GET',
  headers: { Authorization: 'Bearer usr_123' } /* 👈 */,
})
const body = await res.json() /* { greeting: 'Hello Verc!' } */

Examples

For advanced use-cases, please find examples in our complete test suite.

With Express

Please see full example here.

import { createExpressMiddleware } from '@trpc/server/adapters/express'
import express from 'express'
import { createOpenApiExpressMiddleware } from 'trpc-swagger'

import { appRouter } from '../appRouter'

const app = express()

app.use('/api/trpc', createExpressMiddleware({ router: appRouter }))
app.use('/api', createOpenApiExpressMiddleware({ router: appRouter })) /* 👈 */

app.listen(3000)

With Next.js

Please see full example here.

// pages/api/[...trpc].ts
import { createOpenApiNextHandler } from 'trpc-swagger'

import { appRouter } from '../../server/appRouter'

export default createOpenApiNextHandler({ router: appRouter })

With AWS Lambda

Please see full example here.

import { createOpenApiAwsLambdaHandler } from 'trpc-swagger'

import { appRouter } from './appRouter'

export const openApi = createOpenApiAwsLambdaHandler({ router: appRouter })

With Fastify

Please see full example here.

import { fastifyTRPCPlugin } from '@trpc/server/adapters/fastify'
import Fastify from 'fastify'
import { fastifyTRPCOpenApiPlugin } from 'trpc-swagger'

import { appRouter } from './router'

const fastify = Fastify()

async function main() {
  await fastify.register(fastifyTRPCPlugin, { router: appRouter })
  await fastify.register(fastifyTRPCOpenApiPlugin, { router: appRouter }) /* 👈 */

  await fastify.listen({ port: 3000 })
}

main()

Types

GenerateOpenApiDocumentOptions

Please see full typings here.

Property	Type	Description	Required
title	string	The title of the API.	true
description	string	A short description of the API.	false
version	string	The version of the OpenAPI document.	true
baseUrl	string	The base URL of the target server.	true
docsUrl	string	A URL to any external documentation.	false
tags	string[]	A list for ordering endpoint groups.	false
securitySchemes	Record<string, SecuritySchemeObject>	Defaults to Authorization header with Bearer scheme	false

OpenApiMeta

Please see full typings here.

Property	Type	Description	Required	Default
enabled	boolean	Exposes this procedure to trpc-swagger adapters and on the OpenAPI document.	false	true
method	HttpMethod	HTTP method this endpoint is exposed on. Value can be GET, POST, PATCH, PUT or DELETE.	true	undefined
path	string	Pathname this endpoint is exposed on. Value must start with /, specify path parameters using {}.	true	undefined
protect	boolean	Requires this endpoint to use a security scheme.	false	false
summary	string	A short summary of the endpoint included in the OpenAPI document.	false	undefined
description	string	A verbose description of the endpoint included in the OpenAPI document.	false	undefined
tags	string[]	A list of tags used for logical grouping of endpoints in the OpenAPI document.	false	undefined
headers	ParameterObject[]	An array of custom headers to add for this endpoint in the OpenAPI document.	false	undefined
contentTypes	ContentType[]	A set of content types specified as accepted in the OpenAPI document.	false	['application/json']
extraResponses	ResponsesObject*	An array of custom responses to add for this endpoint in the OpenAPI document in addition to the default response.	false	undefined
deprecated	boolean	Whether or not to mark an endpoint as deprecated	false	false

• The content field in ResponsesObject is expected to be a z.ZodType

CreateOpenApiNodeHttpHandlerOptions

Please see full typings here.

Property	Type	Description	Required
router	Router	Your application tRPC router.	true
createContext	Function	Passes contextual (ctx) data to procedure resolvers.	false
responseMeta	Function	Returns any modifications to statusCode & headers.	false
onError	Function	Called if error occurs inside handler.	false
maxBodySize	number	Maximum request body size in bytes (default: 100kb).	false

---

Still using tRPC v9? See our .interop() example.

License

Distributed under the MIT License. See LICENSE for more information.