next-connect
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    0.11.0 • Public • Published

    next-connect

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    The smol method routing and middleware for Next.js (also works in other frameworks). Powered by trouter.

    Features

    • Compatible with Express.js middleware and router => Drop-in replacement for Express.js.
    • Lightweight (~ 3KB) => Suitable for serverless environment.
    • 5x faster than Express.js with no overhead
    • Works with async handlers (with error catching)
    • TypeScript support

    Installation

    npm install next-connect
    // or
    yarn add next-connect

    Usage

    next-connect is often used in API Routes:

    // pages/api/hello.js
    import nc from "next-connect";
    
    const handler = nc({
      onError: (err, req, res, next) => {
        console.error(err.stack);
        res.status(500).end("Something broke!");
      },
      onNoMatch: (req, res, next) => {
        res.status(404).end("Page is not found");
      },
    })
      .use(someMiddleware())
      .get((req, res) => {
        res.send("Hello world");
      })
      .post((req, res) => {
        res.json({ hello: "world" });
      })
      .put(async (req, res) => {
        res.end("async/await is also supported!");
      })
      .patch(async (req, res) => {
        throw new Error("Throws me around! Error can be caught and handled.");
      });
    
    export default handler;

    For quick migration from Custom Express server, simply replacing express() and express.Router() with nc() and follow the match multiple routes recipe.

    For usage in pages with getServerSideProps, see .run.

    See an example in nextjs-mongodb-app (CRUD, Authentication with Passport, and more)

    TypeScript

    By default, the base interfaces of req and res are IncomingMessage and ServerResponse. When using in API Routes, you would set them to NextApiRequest and NextApiResponse by providing the generics to the factory function like so:

    import { NextApiRequest, NextApiResponse } from "next";
    import nc from "next-connect";
    
    const handler = nc<NextApiRequest, NextApiResponse>();

    In each handler, you can also define custom properties to req and res (such as req.user or res.cookie) like so:

    interface ExtendedRequest {
      user: string;
    }
    interface ExtendedResponse {
      cookie(name: string, value: string): void;
    }
    
    handler.post<ExtendedRequest, ExtendedResponse>((req, res) => {
      req.user = "Anakin";
      res.cookie("sid", "8108");
    });

    API

    The API is similar to Express.js with several differences:

    • It does not include any helper methods or template engine (you can incorporate them using middleware).
    • It does not support error-handling middleware pattern. Use options.onError instead.

    It is more like good ol' connect (hence the name) with method routing.

    nc(options?)

    Initialize an instance of next-connect.

    options.onError

    Important: It is strongly recommended to set this option, since the default does not report the error to the terminal.

    Accepts a function as a catch-all error handler; executed whenever a middleware throws an error. By default, it responds with status code 500 and an error message if any.

    function onError(err, req, res, next) {
      logger.log(err);
      // OR: console.error(err);
    
      res.status(500).end(err.toString());
      // OR: you may want to continue
      next();
    }
    
    const handler = nc({ onError });
    
    handler
      .use((req, res, next) => {
        throw new Error("oh no!");
        // or use next
        next(Error("oh no"));
      })
      .use((req, res) => {
        // this will run if next() is called in onError
        res.end("error no more");
      });

    options.onNoMatch

    Accepts a function of (req, res) as a handler when no route is matched. By default, it responds with 404 status and not found body.

    function onNoMatch(req, res) {
      res.status(404).end("page is not found... or is it");
    }
    
    const handler = nc({ onNoMatch });

    options.attachParams

    Passing true will attach params object to req. By default, it does not set to req.params.

    const handler = nc({ attachParams: true });
    
    handler.get("/users/:userId/posts/:postId", (req, res) => {
      // Visiting '/users/12/posts/23' will render '{"userId":"12","postId":"23"}'
      res.send(req.params);
    });

    .use(base, ...fn)

    base (optional) - match all route to the right of base or match all if omitted. (Note: If used in Next.js, this is often omitted)

    fn(s) are functions of (req, res[, next]) or an instance of next-connect, where it will act as a sub application.

    // Mount a middleware function
    handler.use((req, res, next) => {
      req.hello = "world";
      next(); // call to proceed to next in chain
    });
    
    // Or include a base
    handler.use("/foo", fn); // Only run in /foo/**
    
    // Mount an instance of next-connect
    const common = nc().use(midd1).use("/", midd2); // good for common middlewares
    const auth = nc().use("/dashboard", checkAuth);
    const subapp = nc().get(getHandle).post("/baz", postHandle).put("/", putHandle);
    handler
      // `midd1` and `midd2` runs everywhere
      .use(common)
      // `checkAuth` only runs on /dashboard/*
      .use(auth)
      // `getHandle` runs on /foo/*
      // `postHandle` runs on /foo/baz
      // `putHandle` runs on /foo
      .use("/foo", subapp);
    
    // You can use a library too.
    handler.use(passport.initialize());

    .METHOD(pattern, ...fns)

    METHOD is a HTTP method (GET, HEAD, POST, PUT, PATCH, DELETE, OPTIONS, TRACE) in lowercase.

    pattern (optional) - match all route based on supported pattern or match all if omitted.

    fn(s) are functions of (req, res[, next]). This is ideal to be used in API Routes.

    handler.get("/api/user", (req, res, next) => {
      res.json(req.user);
    });
    handler.post("/api/users", (req, res, next) => {
      res.end("User created");
    });
    handler.put("/api/user/:id", (req, res, next) => {
      // https://nextjs.org/docs/routing/dynamic-routes
      res.end(`User ${req.query.id} updated`);
    });
    handler.get((req, res, next) => {
      res.end("This matches whatever route");
    });

    However, since Next.js already handles routing (including dynamic routes), we often omit pattern in .METHOD.

    Note: You should understand Next.js file-system based routing. eg: having a handler.put("/api/foo") inside page/api/index.js does not serve that handler at /api/foo.

    .all(pattern, ...fns)

    Same as .METHOD but accepts any methods.

    .run(req, res)

    Runs req and res the middleware and returns a promise. It will not render 404 on not found or onError on error.

    This can be useful in getServerSideProps.

    // page/index.js
    export async function getServerSideProps({ req, res }) {
      const handler = nc().use(passport.initialize()).post(postMiddleware);
      try {
        await handler.run(req, res);
      } catch (e) {
        // handle the error
      }
      // do something with the upgraded req and res
      return {
        props: { user: req.user },
      };
    }

    Common errors

    1. DO NOT reuse the same instance of nc like the below pattern:
    // middleware/common
    export default nc().use(a).use(b);
    
    // api/foo
    import Handler from "middleware/common";
    export default Handler.get(x);
    
    // api/bar
    import Handler from "middleware/common";
    export default Handler.get(y);

    This is because in each API Route, the same NextConnect instance is mutated, leading to undefined behaviors. If you want to achieve the something like that, try rewriting the base instance as a factory function to avoid reusing the same instance:

    // middleware/common
    export default function base() {
      return nc().use(a).use(b);
    }
    
    // api/foo
    import base from "middleware/common";
    export default base().get(x);
    
    // api/bar
    import base from "middleware/common";
    export default base().get(y);
    1. DO NOT use response function like res.(s)end or res.redirect inside getServerSideProps.
    // page/index.js
    const handler = nc()
      .use((req, res) => {
        // BAD: res.redirect is not a function (not defined in `getServerSideProps`
        res.redirect("foo");
      })
      .use((req, res) => {
        // BAD: `getServerSideProps` gives undefined behavior if we try to send response
        res.end("bar");
      });
    
    export async function getServerSideProps({ req, res }) {
      await handler.run(req, res);
      return {
        props: {},
      };
    }

    Recipes

    Next.js

    Match multiple routes

    If you created the file /api/<specific route>.js folder, the handler will only run on that specific route.

    If you need to create all handlers for all routes in one file (similar to Express.js). You can use Optional catch all API routes.

    // pages/api/[[...slug]].js
    import nc from "next-connect";
    
    const handler = nc({ attachParams: true })
      .use("/api/hello", someMiddleware())
      .get("/api/user/:userId", (req, res) => {
        res.send(`Hello ${req.params.userId}`);
      });
    
    export default handler;

    While this allows quick migration from Express.js, consider seperating routes into different files (/api/user/[userId].js, /api/hello.js) in the future.

    Using in other frameworks

    next-connect supports any frameworks and runtimes that support (req, res) => void handler.

    Micro
    const { send } = require("micro");
    const nc = require("next-connect");
    
    module.exports = nc()
      .use(middleware)
      .get((req, res) => {
        res.end("Hello World!");
      })
      .post((req, res) => {
        send(res, 200, { hello: "world" });
      });
    Vercel
    const nc = require("next-connect");
    
    module.exports = nc()
      .use(middleware)
      .get((req, res) => {
        res.send("Hello World!");
      })
      .post((req, res) => {
        res.json({ hello: "world" });
      });
    Node.js HTTP / HTTP2 Server
    const http = require("http");
    // const http2 = require('http2');
    const nc = require("next-connect");
    
    const handler = nc()
      .use(middleware)
      .get((req, res) => {
        res.end("Hello world");
      })
      .post((req, res) => {
        res.setHeader("content-type", "application/json");
        res.end(JSON.stringify({ hello: "world" }));
      });
    
    http.createServer(handler).listen(PORT);
    // http2.createServer(handler).listen(PORT);

    Contributing

    Please see my contributing.md.

    License

    MIT

    Install

    npm i next-connect

    DownloadsWeekly Downloads

    35,469

    Version

    0.11.0

    License

    MIT

    Unpacked Size

    24.9 kB

    Total Files

    9

    Last publish

    Collaborators

    • hoangvvo