Question 307394 in Javascript Question posted in
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Javascript – Is it possible to have different express middleware for different handlers in the same route path?

I would like to have different routes under an /api path with different middleware handlers. Specifically different API routes should allow different ways of authenticating.

I thought I could nest different API routes under two different Routers with different middleware:

const express = require("express");

const app = express();
const port = 4000;

const one = express.Router();
one.use((req, res, next) => {
  console.log("one");
  next();
});
one.get("/api/one", (req, res) => {
  console.log("/api/one");
  res.send("one");
});

// ---

const two = express.Router();
two.use((req, res, next) => {
  console.log("two");
  next();
});
two.get("/api/two", (req, res) => {
  console.log("/api/two");
  res.send("two");
});

// ---

app.get("/", (req, res) => {
  res.send("Hello World!");
});
app.use(one);
app.use(two);

app.listen(port, () => {
  console.log(`Example app listening on port ${port}`);
});

I would expect that one would get logged when navigating to /api/one and two gets logged when navigating to /api/two, however both middlewares get run when navigating to /api/two:

Example app listening on port 4000
one
/api/one
one
two
/api/two

Is there a way to achieve what I’m looking for without listing the different middleware for each individual API route?

Tags:

2

Answers


  1. 0

    The best I can think of here is to use different path prefixes, the router middleware will only get triggered for the specific route prefix.

    const express = require("express");

const app = express();
const port = 4000;

const one = express.Router();
one.use((req, res, next) => {
  console.log("one");
  next();
});
one.get("/one", (req, res) => {
  console.log("/api/one");
  res.send("one");
});

const two = express.Router();
two.use((req, res, next) => {
  console.log("two");
  next();
});
two.get("/two", (req, res) => {
  console.log("/api/two");
  res.send("two");
});

app.get("/", (req, res) => {
  res.send("Hello World!");
});

// Different prefix
app.use("/api1", one);
app.use("/api2", two);

app.listen(port, () => {
  console.log(`Example app listening on port ${port}`);
});
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  2. 0

    Yes you can do this. Express allows multiple routers and you can mount them at different paths. A simple example would be:

    RouterOne.cjs

    const express = require("express");
const one = express.Router();
one.get("/", (req, res) => {
  console.log("/api/one");
  res.send("one");
});
module.exports = one;

    RouterTwo.cjs

    const express = require("express");
const two = express.Router();
two.get("/", (req, res) => {
  console.log("/api/two");
  res.send("two");
});
module.exports = two;

    app.js

    const express = require("express");
const one = require("./RouterOne.cjs");
const two = require("./RouterTwo.cjs");
function authOne (req, res, next) {
    console.log('Middleware: authOne');
    next();
}
function authTwo (req, res, next) {
    console.log('Middleware: authTwo');
    next();
}
app.use('/api/one', authOne, one);
app.use('/api/two', authTwo, two);
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