Cannot GET /foo when using express.Router()

Question

I'm trying to figure out why the routing doesn't work if I use expressjs, I have this code:

const express = require('express');
const app = express();
const router = express.Router();

app.get('/foo', function (req, res) {
    res.send('Hello World.')
});

the code above works well, but if I replace the route with this:

router.get('/foo', function(req, res, next) {
    res.send('This is api.')
});

I get:

Cannot GET /foo when using express.Router()

Is this code in your root server file (app.js / index.js) or in another file? — Henry Woody, Mar 04 '19 at 19:46
@sfarzoso when you use the router you need to make sure you also do `app.use(router)` — James, Mar 04 '19 at 19:47

score 2 · Accepted Answer · answered Mar 04 '19 at 19:50

2

You are missing the following: app.use(router); Towards the bottom of your code. You'll also need app.listen(3000); Or whatever port you want to run your application on.

Full example:

const express = require('express');
const app = express();
const router = express.Router();

router.get('/foo', function (req, res, next) {
    res.send('This is api.')
});

app.use(router);
app.listen(3000);

answered Mar 04 '19 at 19:50

Bryan

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just a question: is better use router or app with post, get ...? – sfarzoso Mar 04 '19 at 19:56
@sfarzoso Depends on how complicated your app is. Maybe check out https://stackoverflow.com/questions/28305120/differences-between-express-router-and-app-get to get some ideas. – Bryan Mar 04 '19 at 20:01

score 1 · Answer 2 · answered Mar 04 '19 at 19:51

You need to configure each router properly in order to use it in Express.

In your root server file (index.js/app.js) you need to register the router with the app. For example:

const express = require("express");
const app = express();

const fooRouter = require("./routes/foo");
app.use("/foo", fooRouter);

Then in routes/foo.js you can use your code as before ("but note that route paths will be relative to "/foo" a this point), but you also need to export the router. For example:

const express = require("express");
const router = express.Router();

router.get("/bar", (req, res) => {
    // ...
});

module.exports = router;

Where the final route will be "/foo/bar". For just "/foo", you can define a handler for "/" within foo.js.

Cannot GET /foo when using express.Router()

2 Answers2