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Basic usage

// pages/api/user.ts
class User {
  // GET /api/user
  @Get()
  async fetchUser(@Query('id') id: string) {
    const user = await DB.findUserById(id);

    if (!user) {
      throw new NotFoundException('User not found.');
    }

    return user;
  }

  // POST /api/user
  @Post()
  @HttpCode(201)
  async createUser(@Body(ValidationPipe) body: CreateUserDto) {
    return await DB.createUser(body.email);
  }
}

export default createHandler(User);

💡 Read more about validation here

export default async (req: NextApiRequest, res: NextApiResponse) => {
  if (req.method === 'GET') {
    const user = await DB.findUserById(req.query.id);
    if (!user) {
      return res.status(404).json({
        statusCode: 404,
        message: 'User not found'
      })
    }

    return res.json(user);
  } else if (req.method === 'POST') {
    // Very primitive e-mail address validation.
    if (!req.body.email || (req.body.email && !req.body.email.includes('@'))) {
      return res.status(400).json({
        statusCode: 400,
        message: 'Invalid e-mail address.'
      })
    }

    const user = await DB.createUser(req.body.email);
    return res.status(201).json(user);
  }

  res.status(404).json({
    statusCode: 404,
    message: 'Not Found'
  });
}

Motivation

Building serverless functions declaratively with classes and decorators makes dealing with Next.js API routes easier and brings order and sanity to your /pages/api codebase.

The structure is heavily inspired by NestJS, which is an amazing framework for a lot of use cases. On the other hand, a separate NestJS repo for your backend can also bring unneeded overhead and complexity to projects with a smaller set of backend requirements. Combining the structure of NestJS, with the ease of use of Next.js, brings the best of both worlds for the right use case.

If you are not familiar with Next.js or NestJS and want some more information (or need to be convinced), check out the article Awesome Next.js API Routes with next-api-decorators by @tn12787

Installation

Visit https://next-api-decorators.vercel.app/docs/#installation to get started.

Documentation

Refer to our docs for usage topics:

Validation

Route matching

Using middlewares

Custom middlewares

Pipes

Exceptions

Available decorators

Class decorators

| | Description | | ----------------------------------------- | -------------------------------------------------------------- | | @SetHeader(name: string, value: string) | Sets a header name/value into all routes defined in the class. | | @UseMiddleware(...middlewares: Middleware[]) | Registers one or multiple middlewares for all the routes defined in the class. |

Method decorators

| | Description | | ----------------------------------------- | ------------------------------------------------- | | @Get(path?: string) | Marks the method as GET handler. | | @Post(path?: string) | Marks the method as POST handler. | | @Put(path?: string) | Marks the method as PUT handler. | | @Delete(path?: string) | Marks the method as DELETE handler. | | @Patch(path?: string) | Marks the method as PATCH handler. | | @SetHeader(name: string, value: string) | Sets a header name/value into the route response. | | @HttpCode(code: number) | Sets the http code in the route response. | | @UseMiddleware(...middlewares: Middleware[]) | Registers one or multiple middlewares for the handler. |

Parameter decorators

| | Description | | ----------------------- | ------------------------------------------- | | @Req() | Gets the request object. | | @Res()* | Gets the response object. | | @Body() | Gets the request body. | | @Query(key: string) | Gets a query string parameter value by key. | | @Header(name: string) | Gets a header value by name. | | @Param(key: string) | Gets a route parameter value by key. |

* Note that when you inject @Res() in a method handler you become responsible for managing the response. When doing so, you must issue some kind of response by making a call on the response object (e.g., res.json(...) or res.send(...)), or the HTTP server will hang.