next-rest-framework v6.0.0

Table of contents

• Table of contents
• Overview
• Features
  • Lightweight, type-safe, easy to use
• Requirements
• Installation
• Getting started
  • Create docs endpoint
    • App router docs route:
    • Pages router docs API route:
  • Create endpoint
    • REST endpoints
      • App router route:
      • Pages router API route:
    • Form endpoints
      • App router form route:
      • Pages router form API route:
    • RPC endpoints
      • App router RPC route:
      • Pages router RPC API route:
  • Client
    • REST client
    • RPC client
• API reference
  • Docs handler options
  • Docs config
  • REST
    • Route handler options
    • Route operations
      • Route operation input
      • Route operation outputs
      • Route operation middleware
      • Route operation handler
  • RPC
    • RPC route handler options
    • RPC operations
      • RPC operation input
      • RPC operation outputs
      • RPC operation middleware
      • RPC operation handler
• CLI
• Changelog
• Contributing
• License

Overview

Next REST Framework is an open-source, opinionated, lightweight, easy-to-use set of tools to build type-safe, self-documenting APIs with Next.js. Building OpenAPI specification-compliant APIs can be cumbersome and slow but Next REST Framework makes this easy with auto-generated OpenAPI documents and docs using TypeScript and object schemas.

• Live demo
• Docs

This is a monorepo containing the following packages / projects:

1. The primary next-rest-framework package
2. An example application for live demo and local development

Features

Lightweight, type-safe, easy to use

• Designed to work with TypeScript so that your requests and responses are strongly typed.
• Supports API endpoints using both RESTful and RPC principles.
• Object-schema validation with Zod. The object schemas are automatically converted to JSON schema format for the auto-generated OpenAPI specification.
• Auto-generated and extensible openapi.json spec file from your business logic.
• Auto-generated Redoc and/or SwaggerUI documentation frontend.
• Works with Next.js Middleware and other server-side libraries, like NextAuth.js.
• Supports both Next.js app router and pages router, even at the same time.
• Supports Edge runtime.
• Fully customizable and compatible with any existing Next.js project.

Requirements

• Node.js v18.x. If you have an API using File or FormData web APIs, you might need Node v20.x, see: https://github.com/vercel/next.js/discussions/56032

You also need the following dependencies installed in you Next.js project:

• Next.js >= v12
• Optional (needed for validating input): Zod >= v3
• Optional: TypeScript >= v3
• Optional (needed when using the CLI commands and using TypeScript): tsx >= v4
• Optional (needed if working with forms): zod-form-data >= v2

Installation

npm install next-rest-framework

Getting started

Create docs endpoint

To get access to the auto-generated documentation, initialize the docs endpoint somewhere in your codebase. You can also skip this step if you don't want to expose a public API documentation.

App router docs route:

// src/app/api/v2/route.ts

import { docsRoute } from 'next-rest-framework';

// export const runtime = 'edge'; // Edge runtime is supported.

export const { GET } = docsRoute({
  // deniedPaths: [...] // Ignore endpoints from the generated OpenAPI spec.
  // allowedPaths: [...], // Explicitly set which endpoints to include in the generated OpenAPI spec.
  // Override and customize the generated OpenAPI spec.
  openApiObject: {
    info: {
      title: 'My API',
      version: '1.0.0',
      description: 'My API description.'
    }
    // ...
  },
  // openApiJsonPath: '/openapi.json', // Customize the path where the OpenAPI spec will be generated.
  // Customize the rendered documentation.
  docsConfig: {
    provider: 'redoc', // redoc | swagger-ui
    title: 'My API',
    description: 'My API description.'
    // ...
  }
});

Pages router docs API route:

// src/pages/api/v1/index.ts

import { docsApiRoute } from 'next-rest-framework';

export default docsApiRoute({
  // See configuration options from above.
});

This is enough to get you started. Now you can access the API documentation in your browser. Running npx next-rest-framework generate in the project root will generate the openapi.json OpenAPI specification file, located in the public folder by default. You can create multiple docs endpoints if needed and specify which config to use for the CLI. See the full configuration options of this endpoint in the Docs handler options section.

Create endpoint

REST endpoints

App router route:

// src/app/api/v2/todos/route.ts

import { TypedNextResponse, route, routeOperation } from 'next-rest-framework';
import { z } from 'zod';

// export const runtime = 'edge'; // Edge runtime is supported.

const MOCK_TODOS = [
  {
    id: 1,
    name: 'TODO 1',
    completed: false
  }
  // ...
];

const todoSchema = z.object({
  id: z.number(),
  name: z.string(),
  completed: z.boolean()
});

export const { GET, POST } = route({
  getTodos: routeOperation({
    method: 'GET'
  })
    .outputs([
      {
        status: 200,
        contentType: 'application/json',
        body: z.array(todoSchema)
      }
    ])
    .handler(() => {
      return TypedNextResponse.json(MOCK_TODOS, {
        status: 200
      });
    }),

  createTodo: routeOperation({
    method: 'POST'
  })
    .input({
      contentType: 'application/json',
      body: z.object({
        name: z.string()
      })
    })
    .outputs([
      {
        status: 201,
        contentType: 'application/json',
        body: z.string()
      },
      {
        status: 401,
        contentType: 'application/json',
        body: z.string()
      }
    ])
    // Optional middleware logic executed before request validation.
    .middleware((req) => {
      if (!req.headers.get('very-secure')) {
        return TypedNextResponse.json('Unauthorized', {
          status: 401
        });
      }
    })
    .handler(async (req) => {
      const { name } = await req.json();

      return TypedNextResponse.json(`New TODO created: ${name}`, {
        status: 201
      });
    })
});

The TypedNextResponse ensures that the response status codes and content-type headers are type-checked against the defined outputs. You can still use the regular NextResponse if you prefer to have less type-safety.

When using the default nodejs runtime with app router routes (docsRoute or route), you may encounter the Dynamic server usage Next.js error when running next build. In that case you should force the route to be dynamically rendered with the dynamic option:

export const dynamic = 'force-dynamic';

Pages router API route:

// src/pages/api/v1/todos/index.ts

import { apiRoute, apiRouteOperation } from 'next-rest-framework';
import { z } from 'zod';

const MOCK_TODOS = [
  {
    id: 1,
    name: 'TODO 1',
    completed: false
  }
  // ...
];

const todoSchema = z.object({
  id: z.number(),
  name: z.string(),
  completed: z.boolean()
});

export default apiRoute({
  getTodos: apiRouteOperation({
    method: 'GET'
  })
    .outputs([
      {
        status: 200,
        contentType: 'application/json',
        body: z.array(todoSchema)
      }
    ])
    .handler((_req, res) => {
      res.status(200).json(MOCK_TODOS);
    }),

  createTodo: apiRouteOperation({
    method: 'POST'
  })
    .input({
      contentType: 'application/json',
      body: z.object({
        name: z.string()
      })
    })
    .outputs([
      {
        status: 201,
        contentType: 'application/json',
        body: z.string()
      },
      {
        status: 401,
        contentType: 'application/json',
        body: z.string()
      }
    ])
    // Optional middleware logic executed before request validation.
    .middleware((req, res) => {
      if (!req.headers['very-secure']) {
        res.status(401).json('Unauthorized');
      }
    })
    .handler((req, res) => {
      const { name } = req.body;
      // Create a new TODO.
      res.status(201).json(`New TODO created: ${name}`);
    })
});

After running next-rest-framework generate, all of above type-safe endpoints will be auto-generated to your OpenAPI spec and exposed in the documentation:

Form endpoints

App router form route:

When specifying request input schema for validation, the content type header determines what kind of schema you can use to validate the request body. When using application/json, a plain Zod object schema can be used for the validation. When using application/x-www-form-urlencoded or multipart/form-data content types, a zod-form-data schema must be used:

// src/app/api/v2/form-data/url-encoded/route.ts

import { TypedNextResponse, route, routeOperation } from 'next-rest-framework';
import { zfd } from 'zod-form-data';

// export const runtime = 'edge'; // Edge runtime is supported.

const formSchema = zfd.formData({
  text: zfd.text()
});

export const { POST } = route({
  urlEncodedFormData: routeOperation({
    method: 'POST'
  })
    .input({
      contentType: 'application/x-www-form-urlencoded',
      body: formSchema // A zod-form-data schema is required.
    })
    .outputs([
      {
        status: 200,
        contentType: 'application/octet-stream',
        body: formSchema
      }
    ])
    .handler(async (req) => {
      const { text } = await req.json();
      // const formData = await req.formData(); // Form can also be parsed as form data.

      // Type-checked response.
      return TypedNextResponse.json({
        text
      });
    })
});

For multipart/form-data app router example, see this example.

Pages router form API route:

A form API route with pages router works similarly as the App router form route using a zod-form-data schema:

// src/pages/api/v1/form-data/url-encoded/index.ts

import { apiRoute, apiRouteOperation } from 'next-rest-framework';
import { zfd } from 'zod-form-data';

const formSchema = zfd.formData({
  text: zfd.text()
});

export default apiRoute({
  urlEncodedFormData: apiRouteOperation({
    method: 'POST'
  })
    .input({
      contentType: 'application/x-www-form-urlencoded',
      body: formSchema // A zod-form-data schema is required.
    })
    .outputs([
      {
        status: 200,
        contentType: 'application/json',
        body: formSchema
      }
    ])
    .handler((req, res) => {
      const formData = req.body;

      res.json({
        text: formData.get('text')
      });
    })
});

For multipart/form-data pages router example, see this example.

The form routes will also be included in your OpenAPI spec after running next-rest-framework generate.

RPC endpoints

Next REST Framework also supports writing RPC-styled APIs that support JSON and form data. A recommended way is to write your RPC operations in a separate server-side module where they can be consumed both by the RPC endpoints and directly as server-side functions (server actions):

// src/app/actions.ts

'use server';

import { rpcOperation } from 'next-rest-framework';
import { z } from 'zod';
import { zfd } from 'zod-form-data';

// The RPC operations can be used as server-actions and imported in the RPC route handlers.

const MOCK_TODOS = [
  {
    id: 1,
    name: 'TODO 1',
    completed: false
  }
  // ...
];

const todoSchema = z.object({
  id: z.number(),
  name: z.string(),
  completed: z.boolean()
});

export const getTodos = rpcOperation()
  .outputs([
    {
      body: z.array(todoSchema)
    }
  ])
  .handler(() => {
    return MOCK_TODOS;
  });

export const getTodoById = rpcOperation()
  .input({
    contentType: 'application/json',
    body: z.string()
  })
  .outputs([
    {
      body: z.object({
        error: z.string()
      })
    },
    {
      body: todoSchema
    }
  ])
  .handler((id) => {
    const todo = MOCK_TODOS.find((t) => t.id === Number(id));

    if (!todo) {
      return { error: 'TODO not found.' };
    }

    return todo;
  });

export const createTodo = rpcOperation()
  .input({
    contentType: 'application/json',
    body: z.object({
      name: z.string()
    })
  })
  .outputs([{ body: todoSchema }])
  .handler(async ({ name }) => {
    const todo = { id: 4, name, completed: false };
    return todo;
  });

export const deleteTodo = rpcOperation()
  .input({
    contentType: 'application/json',
    body: z.string()
  })
  .outputs([
    { body: z.object({ error: z.string() }) },
    { body: z.object({ message: z.string() }) }
  ])
  .handler((id) => {
    const todo = MOCK_TODOS.find((t) => t.id === Number(id));

    if (!todo) {
      return {
        error: 'TODO not found.'
      };
    }

    return { message: 'TODO deleted.' };
  });

const formSchema = zfd.formData({
  text: zfd.text()
});

export const formDataUrlEncoded = rpcOperation()
  .input({
    contentType: 'application/x-www-form-urlencoded',
    body: formSchema // A zod-form-data schema is required.
  })
  .outputs([{ body: formSchema }])
  .handler((formData) => {
    return {
      text: formData.get('text')
    };
  });

const multipartFormSchema = zfd.formData({
  text: zfd.text(),
  file: zfd.file()
});

export const formDataMultipart = rpcOperation()
  .input({
    contentType: 'multipart/form-data',
    body: multipartFormSchema // A zod-form-data schema is required.
  })
  .outputs([
    {
      body: z.custom<File>(),
      // The binary file cannot described with a Zod schema so we define it by hand for the OpenAPI spec.
      bodySchema: {
        type: 'string',
        format: 'binary'
      }
    }
  ])
  .handler((formData) => {
    const file = formData.get('file');
    return file;
  });

Now you can consume the RPC operations directly in your server-side components:

'use server';

import { getTodos, createTodo } from 'src/app/actions';

export default async function Page() {
  const todos = await getTodos();

  const createTodo = async (name: string) => {
    'use server';
    return createTodo({ name });
  };

  // ...
}

App router RPC route:

The file path to an RPC route must end with /[operationId]/route.ts. Simply import the RPC operations in to your RPC route handler:

// src/app/api/rpc/[operationId]/route.ts

import {
  createTodo,
  deleteTodo,
  getTodoById,
  getTodos,
  formDataUrlEncoded,
  formDataMultipart
} from 'src/app/actions';
import { rpcRoute } from 'next-rest-framework';

// export const runtime = 'edge'; // Edge runtime is supported.

export const { POST } = rpcRoute({
  getTodos,
  getTodoById,
  createTodo,
  deleteTodo,
  formDataUrlEncoded,
  formDataMultipart
  // You can also inline the RPC operations in this object if you don't need to use server actions.
});

export type RpcClient = typeof POST.client;

Pages router RPC API route:

The filename of an RPC API route must be [operationId].ts.

// src/pages/api/rpc/[operationId].ts

import { rpcApiRoute } from 'next-rest-framework';
// import { ... } from 'src/app/actions';

const handler = rpcApiRoute({
  // ...
  // Exactly the same as the app router example above.
});

export default handler;

export type RpcClient = typeof handler.client;

The RPC routes will also be included in your OpenAPI spec after running next-rest-framework generate.

Client

REST client

To achieve end-to-end type-safety with your REST endpoints, you can use any client implementation that relies on the generated OpenAPI specification, e.g. openapi-client-axios.

RPC client

While you can consume your RPC operations directly as server actions in your React server components, for client-rendered components you can use the strongly-typed rpcClient, passing in the exported type from your RPC endpoint as a generic parameter:

'use client';

import { rpcClient } from 'next-rest-framework/rpc-client';
import { type RpcClient } from 'app/api/rpc/[operationId]';

const client = rpcClient<RpcClient>({
  url: 'http://localhost:3000/api/rpc'
});

export default function Page() {
  // ...

  useEffect(() => {
    client
      .getTodos()
      .then(() => {
        // ...
      })
      .catch(console.error);
  }, []);

  const createTodo = async (name: string) => {
    const todo = client.createTodo({ name });
    // ...
  };

  // ...
}

The rpcClient calls can also be easily integrated with any data fetching framework, like React Query or RTKQ.

API reference

Docs handler options

The following options can be passed to the docsRoute (app router) and docsApiRoute (pages router) functions for customizing Next REST Framework:

Docs config

The docs config options can be used to customize the generated docs:

REST

Route handler options

The routeHandler (app router) and apiRouteHandler (pages router) functions allow you to pass an object as the second parameter, where you can define a property called openApiPath. This property is an OpenAPI Path Item Object that can be used to override and extend the auto-generated specification for the given route.

Route operations

The route operation functions routeOperation (app router) and apiRouteOperation (pages router) allow you to define your method handlers for your endpoints. These functions require you to pass an object where you will define the method for the given operation, as well as optionally a property called openApiOperation. This property is an OpenAPI Operation object that can be used to override and extend the auto-generated specification for the given operation. Calling the routeOperation and apiRouteOperation functions allows you to chain your API handler logic with the following functions:

Route operation input

The route operation input function is used for type-checking, validation and documentation of the request, taking in an object with the following properties:

Calling the route operation input function allows you to chain your API handler logic with the Route operation outputs, Route operation middleware and Route operation handler functions.

Route operation outputs

The route operation outputs function is used for type-checking and documentation of the response, taking in an array of objects with the following properties:

Calling the route operation outputs function allows you to chain your API handler logic with the Route operation middleware and Route operation handler functions.

Route operation middleware

The route operation middleware function is executed before validating the request input. The function takes in the same parameters as the Next.js router handler (app router) and API route (pages router) functions. Additionally, as a second parameter this function takes the return value of your last middleware function, defaulting to an empty object. Throwing an error inside a middleware function will stop the execution of the handler and you can also return a custom response like you would do within the Route operation handler function. Calling the route operation middleware function allows you to chain your API handler logic with the Route operation handler function. Alternatively, you may chain up to three middleware functions together:

// App router.
export const { GET } = route({
  getTodos: routeOperation({ method: 'GET' })
    .middleware(() => {
      return { foo: 'bar' };
    })
    .middleware((_req, _ctx, { foo }) => {
      if (myCondition) {
        return NextResponse.json({ error: 'My error.' }, { status: 400 });
      }

      return {
        foo,
        bar: 'baz'
      };
    })
    .handler((_req, _ctx, { foo, bar }) => {
      // ...
    })
});

// Pages router.
export default apiRoute({
  getTodos: routeOperation({ method: 'GET' })
    .middleware(() => {
      return { foo: 'bar' };
    })
    .middleware((req, res, { foo }) => {
      if (myCondition) {
        res.status(400).json({ error: 'My error.' });
        return;
      }

      return {
        foo,
        bar: 'baz'
      };
    })
    .handler((req, res, { foo, bar }) => {
      // ...
    })
});

Route operation handler

The route operation handler function is a strongly-typed function to implement the business logic for your API. The function takes in strongly-typed versions of the same parameters as the Next.js router handler (app router) and API route (pages router) functions. Additionally, as a third parameter this function takes the return value of your last middleware function (see above), defaulting to an empty object.

RPC

RPC route handler options

The rpcRouteHandler (app router) and rpcApiRouteHandler (pages router) functions allow you to pass an object as the second parameter, where you can define a property called openApiPath. This property is an OpenAPI Path Item Object that can be used to override and extend the auto-generated specification for the given route.

RPC operations

The rpcOperation function allows you to define your API handlers for your RPC endpoint. This function allows you to pass an OpenAPI Operation object as a parameter, that can be used to override and extend the auto-generated specification for the given operation. Calling this function allows you to chain your API handler logic with the following functions.

RPC operation input

The RPC operation input function is used for type-checking, validation and documentation of the RPC call, taking in an object with the following properties:

Calling the RPC input function allows you to chain your API handler logic with the RPC operation outputs, RPC middleware and RPC handler functions.

RPC operation outputs

The RPC operation outputs function is used for type-checking and documentation of the response, taking in an array of objects with the following properties:

Calling the RPC operation outputs function allows you to chain your API handler logic with the RPC operation middleware and RPC operation handler functions.

RPC operation middleware

The RPC operation middleware function is executed before validating RPC operation input. The function takes in strongly typed parameters typed by the RPC operation input function. Additionally, as a second parameter this function takes the return value of your last middleware function, defaulting to an empty object. Throwing an error inside a middleware function will stop the execution of the handler. Calling the RPC operation middleware function allows you to chain your RPC API handler logic with the RPC operation handler function. Alternatively, you may chain up to three middleware functions together:

// App router.
export const { POST } = rpcRoute({
  getTodos: rpcOperation()
    .middleware(() => {
      return { foo: 'bar' };
    })
    .middleware((_input, { foo }) => {
      if (myCondition) {
        throw Error('My error.');
      }

      return {
        foo,
        bar: 'baz'
      };
    })
    .handler((_input, { foo, bar }) => {
      // ...
    })
});

// Pages router.
export default rpcApiRoute({
  // ... Same as above.
});

RPC operation handler

The RPC operation handler function is a strongly-typed function to implement the business logic for your API. The function takes in strongly typed parameters typed by the RPC operation input function. Additionally, as a second parameter this function takes the return value of your last middleware function (see above), defaulting to an empty object.

CLI

The CLI commands will parse your Next.js APIs and generate/validate the openapi.json file. If using TypeScript, you will need to install tsx and use it as the Node.js loader for the CLI commands below: npm install --save-dev tsx

• NODE_OPTIONS='--import=tsx' npx next-rest-framework generate to generate the openapi.json file.
• NODE_OPTIONS='--import=tsx' npx next-rest-framework validate to validate that the openapi.json file is up-to-date.

The next-rest-framework validate command is useful to have as part of the static checks in your CI/CD pipeline. Both commands support the following options:

A good practice is to set these in your package.json as both commands are needed:

"scripts": {
  "generate": "NODE_OPTIONS='--import=tsx' next-rest-framework generate",
  "validate": "NODE_OPTIONS='--import=tsx' next-rest-framework validate",
}

Changelog

See the changelog in CHANGELOG.md

Contributing

All contributions are welcome!

License

ISC, see full license in LICENSE.