next-typed-connect

next-typed-connect

A library for creating type-safe APIs in next.js.

Motivation

I wanted to create type-safe APIs in Next.js using zod and also wanted to generate type definition files for client-side use so that I could use intuitive API calls. But I couldn't find a library that met my needs, so I created this library.

Features

• Type-safe API routing
• Type-safe API call
• error handling
• Type definition file generation
• Middleware support

Demo

https://stackblitz.com/edit/next-typescript-32qrbx?embed=1&file=pages/index.tsx&file=pages/api/sample/[id].ts&hideNavigation=1&view=editor

Usage

Installation

## npm
npm install next-typed-connect

## yarn
yarn add next-typed-connect

Server-side

1. Use zod to define the types for body, query, and res.
2. Create routing handling with createRouter.
3. Assign types to the created routing handling with validate.
4. Export the types as GetHandler and PostHandler.

// pages/api/sample.ts
import { ApiHandler, createRouter, validate } from "next-typed-connect";
import { z } from "zod";

/* Schema definition using zod */
const postValidation = {
  body: z.object({
    foo: z.string(),
  }),
  query: z.object({
    bar: z.string().optional(),
  }),
  res: z.object({
    message: z.string(),
  }),
}

const getValidation = {
  query: z.object({
    bar: z.string().optional(),
  }),
  res: z.object({
    message: z.string(),
  }),
}    

/* Routing */
const router = createRouter()

router
  .use((req, res, next) => {
    console.log("middleware");
    return next()
  })
  .post(
    validate(postValidation),
    (req, res) => {
      req.body.foo;
      req.query.bar;
      res.status(200).json({ message: "ok" });
    })
  .get(
    validate(getValidation),
    (req, res) => {
      req.query.bar;
      res.status(200).json({ message: "ok" });
    })

/* Type export */
// the export type name should be as follows
// so that the type definition file can be generated correctly via the command.
export type PostHandler = ApiHandler<typeof postValidation>
export type GetHandler = ApiHandler<typeof getValidation>

/* Routing handling export */
export default router.run()

Error handling

throw error

// pages/api/sample.ts
router
  .post(
    validate(postValidation),
    (req, res) => {
      const session = getSession(req)
      if (!session) {
        throw createError(401, "Unauthorized")
      }
      res.status(200).json({ message: "ok" });
    })

custom error handling

// pages/api/sample.ts

router
  .onError((err, req, res) => {
    // custom error handling
    res.status(err.statusCode).json({ message: err.message });
  })

dynamic routing

Server-side

// pages/api/[id].ts

const getValidation = {
  // 👇 for server side validation
  // 👇 also necessary for client side url construction
  query: z.object({
    id: z.string().optional(),
  }),
}

router
  .get(
    validate(getValidation),
    (req, res) => {
      req.query.id;
      res.status(200).json({ message: "ok" });
    })

Client-side

// client.ts
import { client } from "next-typed-connect";

client.get("/api/[id]", {
  query: {
    id: "1",
  },
})

// url will be /api/1

Type generation

## npm
npx next-typed-connect

## yarn
yarn next-typed-connect

Adding a script to your package.json is convenient.

{
  "scripts": {
    "apigen": "next-typed-connect"
  }
}

npm run apigen

Client-side

import { client } from "next-typed-connect";

// Type-safe API call
const { data, error } = await client.post("/api/sample", {
  query: {
    bar: "baz",
  },
  body: {
    foo: "bar",
  },
})

Command options

The default pages directory is pages, so if you want to change it, you can use the --pagesDir option.

next-typed-connect --pagesDir=src/pages

Option	Description	Default value
--pagesDir	Pages directory	pages
--baseDir	Project directory	.
--distDir	Type definition file output destination	node_modules/.next-typed-connect
--moduleNameSpace	Type definition file module name	.next-typed-connect

Tips

If you want to add session property to Request type, you can use the following code.

// global.d.ts
import { IncomingMessage } from "http";

declare module 'next' {
  export interface NextApiRequest extends IncomingMessage {
    session: Session
  }
}