Route requiring a middleware function - javascript

I'm creating my routes module in nodejs with socket.io
var express = require("express"); // call express
var taskSchema = require("../models/taskModel");
var mongoose = require("mongoose");
var router = express.Router(); // get an instance of the express Router
module.exports = function (io) {
router.use(function (req, res, next) {
io.sockets.emit('payload');
console.log("Something is happening.");
next();
});
router
.route("/tasks")
.post(function (req, res, next) {
...
});
router
.route("/tasks")
.get(function (req, res) {
...
});
};
When I compile server I get this error
TypeError: Router.use() requires a middleware function but got a undefined

It appears to me that the problem is probably in the code that loads this module because you never export the actual router. So, assuming you do app.use() or router.use() in the caller who loads this module, your aren't returning the router from your function so there's no way to hook that router in and you would get the error you see.
I'm guessing that you can fix this by just returning the router from your exported function:
var express = require("express"); // call express
var taskSchema = require("../models/taskModel");
var mongoose = require("mongoose");
var router = express.Router(); // get an instance of the express Router
module.exports = function (io) {
router.use(function (req, res, next) {
io.sockets.emit('payload');
console.log("Something is happening.");
next();
});
router
.route("/tasks")
.post(function (req, res, next) {
...
});
router
.route("/tasks")
.get(function (req, res) {
...
});
return router; // <=========== Add this
};
Then, when you do:
let m = require('yourModule');
router.use(m(io));
Then function will return the router that router.use() will be happy with. You can pass either middleware or a router to .use().
If this guess isn't quite on target, then please show us the code that loads and calls this module.

When that function is called it's gonna return the equivalent of undefined. Also, normally a route is defined before the endpoint. It's typically structured like:
let myRouter = new Router();
Router.use('something', middlewareFunction, someotherprocess);

Related

Parameter express can't be passed with require

app.js
const express = require("express");
const app = express();
app.use("/", require("./routers.js")(app));
app.listen(3000);
router.js
module.exports = function (app) {
console.log(app);
app.get("/", (req, res) => {
res.json(5);
});
};
The error given by the Console is: " TypeError: Router.use() requires a middleware function but got an undefined "
I don't understand why I can't pass the express app(app.js) through routers( in this way I don't redeclare the express and app variable in router.js ).
Don't pass app to routes better to create a new router and pass to the app.
router.js
const express = require("express");
const router = express.Router();
router.get("/", (req, res) => {
res.json(5);
});
module.exports = router;
app.js
app.use("/", require("./routers.js"));
As you mention in the comment, you don't have to add an inside app.use
module.exports = function (app) {
app.get("/", (req, res) => {
res.json(5);
});
};
// app.js
require("./routers.js")(app);
The use method of Express needs a callback of three parameters, not the app itself, so you need something like this:
In routes.js
exports.doSomeThing = function(req, res, next){
console.log("Called endpoint");
res.send("Called endpoint");
}
In your index.js
const Express = require("express");
const app = Express();
const routes = require("./routes");
app.use("/", routes.doSomeThing);
app.listen(3030, () => {
console.log("Listening on port 3030");
});
This approach doesn't need to include the express router but this may not be adecuate for big scale projects I recommend you to read express router documentation:
https://expressjs.com/es/guide/routing.html#express-router

Express route only works after the second try

I am using the express framework for a node.js backend server. I am using the express router to define the different routes.
This is my app.js file:
var express = require('express');
var app = express();
var server = require('http').Server(app);
var cors = require('cors');
app.use(cors());
app.use(express.json());
var route = require('./route');
app.use('/api/', route);
server.listen(3000, () => {
console.log('App running on port 3000!');
});
This is my router route.js:
var express = require('express');
var router = express.Router();
var controller = require('./controller');
router.use(function (req, res, next) {
next();
router.get('/test', function (req, res, next) {
controller.get(req, res, next);
});
});
module.exports = router;
The route itself uses a controller for the logic controller.js
exports.get = function (req, res, next) {
res.send('Hello World');
}
Starting the app with node app.js and calling the defined route http://localhost:3000/api/test will result in a Cannot GET /api/test on the first try. Calling the route a second time however will result in the expected answer hello world.
What is the reason for the first call failing? Why does it work on the second try? Any ideas are appreciated
Because router.use(function (req, res, next) { will only get executed on the first request, and when you call next() the route was not yet added. Afterwards you call router.get(...) which will add the route, so it will be available the next time.
Nevertheless thats just bad, move the .get(...) outside of .use(...) (you can also get rid of it entirely).

Express subrouter returns 404

I have this router (http/api/ping.js):
var express = require('express');
var router = express.Router();
router.get('/ping', function (req, res) {
res.send("You called /api/ping");
});
module.exports = router;
This router is embedded into this router (http/api/index.js):
var express = require('express');
var router = express.Router();
router.get('/', function (req, res) {
res.send('You called /api');
});
router.use('/ping', require('./ping'));
module.exports = router;
And this router is used by my Express.js app (app.js):
var http = require('http');
var express = require('express');
var bodyParser = require('body-parser');
var logger = require('./config').logger;
// Create app
var app = express();
var server = http.createServer(app)
var io = require('socket.io')(server);
// App config
app.use(bodyParser.json());
app.use('/api', require('./http/api'));
// Display requests on console
app.use(function (req, res, next) {
logger.trace(req.method, req._parsedUrl.href);
next()
});
module.exports = {
app: app,
server: server
};
When I run the app, /api returns You called /api, but /api/ping gives me a 404.
I am using Node 6.9.1 and Express ^4.14.0
I think order matters in this scenario. Try putting /ping above the / get route.
router.use('/ping', require('./ping'));
router.get('/', function (req, res) {
res.send('You called /api');
});
Also in your ping route you say the path to your route is /ping you also say it is /ping when you import it to the other router, which would make the path /api/ping/ping
change
router.get('/ping', function (req, res) {
res.send("You called /api/ping");
});
to
router.get('/', function (req, res) {
res.send("You called /api/ping");
});
I think your routing is incorrect on this line
router.use('/ping', require('./ping'));
this will point to http/api/ping/ping
it should be
router.use('/', require('./ping'));

Router.use requires middleware function?

So I'm trying to seperate my login routes in a seperate JS file called login_routes.js
I keep getting this specific error:
TypeError: Router.use() requires middleware function but got a Object
at Function. (/Users/ethanthomas/Desktop/mean-stuff/express-server/node_modules/express/lib/router/index.js:446:13)
Not entirely understanding what it's asking me to implement?
login_routes.js:
var express = require('express');
var app = express();
app.route('/login')
.get(function(req, res, next) {
res.send('this is the login form');
})
.post(function(req, res, next) {
console.log('processing');
res.send('proccessing the login form!');
});
server.js:
var express = require('express');
var app = express();
var path = require('path');
var adminRoutes = require('./app/routes/admin_routes');
var loginRoutes = require('./app/routes/login_routes');
app.use('/admin', adminRoutes);
app.use('/login', loginRoutes);
//send our index.html file to the user for the home page
app.get('/', function(req, res) {
res.sendFile(path.join(__dirname + '/index.html'));
});
//start the server
app.listen(1337);
console.log('leet is the magic port');
Your login_routes.js should look something like this (in the context of express):
var express = require('express');
var router = express.Router();
// GET request to /login
router.get('/', function(req, res, next) {
// do something
});
// POST request to /login
router.post('/', function(req, res, next) {
// do something
});
module.exports = router;
In your app.js you use
var login_routes = require('./login_routes');
...
app.use('/login', login_routes);
...
Have a look at the code generated by the express-generator module. That is a starting point for express webserver apps.
People have already offered hints at the solution in comments.
The first issue is that you need to export your "sub" app from login_routes.js. To do so, change this:
var app = express();
Into this:
var app = module.exports = express();
Secondly, you are—probably unintentionally—creating routes for GET /login/login and POST /login/login. To solve this, use this in login_routes.js:
app.route('/').get(...).post(...);
This is because the root path in your sub app (the one in login_routes.js) will get mapped to the path used in app.use() in your main app (server.js).
Do like this:
login_routes.js:
exports.get = function( req, res ) {
res.send('this is the login form');
};
exports.post = function( req, res ) {
console.log('processing');
res.send('proccessing the login form!');
};
server.js:
var loginRoutes = require('./app/routes/login_routes');
app.get('/login', loginRoutes.get);
app.put('/login', loginRoutes.post);
login_routes.js:
var express = require('express');
var app = express();
app.route('/login')
.get(function(req, res, next) {
res.send('this is the login form');
})
.post(function(req, res, next) {
console.log('processing');
res.send('proccessing the login form!');
});
module.exports = router;
just writ module.exports = router then it will be work

Dynamic routes with different functions in express js

I have loads of router.get functions in my code which I think, could be reduced to a single switch-case function. Here is what I have tried:
function handlerA(req, res) {}
function handlerB(req, res) {}
var routes = {
'/url-one': handlerA,
'/url-two': handlerB
}
router.get('/*', function(req, res) {
var url = req.url;
if (routes[url]) {
routes[url](req, res);
}
});
This works but also, significantly slows my application. Is there any other solution which would not hit the performance of my app?
Thanks
Is there a reason you don't want to use router.get functions? I would guess express.js is internally performing the same logic that you are doing anyway. You are just replacing get functions with handlers.
If you are using similar logic between multiple routes, that may be worth abstracting.
I usually go with a setup like this:
app.js
routes.js
api/
user/
index.js
user.controller.js
user.model.js
image/
index.js
image.controller.js
image.model.js
/api/user/index.js:
var express = require('express');
var controller = require('./user.controller');
var router = express.Router();
router.get('/', controller.index);
router.post('/', controller.create);
module.exports = router;
/api/user/user.controller.js:
var User = require('./user.model');
exports.index = function(req, res) {
// Show list of users
};
exports.create = function (req, res, next) {
// Create user
};
/routes.js:
module.exports = function(app) {
// Insert routes below
app.use('/api/users', require('./api/user'));
app.use('/api/images', require('./api/image'));
// All undefined asset or api routes should return a 404
app.route('/:url(api|auth|components|app|bower_components|assets)/*')
.get(errors[404]);
// All other routes should redirect to the index.html
app.route('/*')
.get(function(req, res) {
res.sendfile(app.get('appPath') + '/index.html');
});
};
And lastly, the /app.js:
// Set default node environment to development
process.env.NODE_ENV = process.env.NODE_ENV || 'development';
var express = require('express');
var mongoose = require('mongoose');
var config = require('./config/environment');
// Connect to database
mongoose.connect(config.mongo.uri, config.mongo.options);
// Populate DB with sample data
if(config.seedDB) { require('./config/seed'); }
// Setup server
var app = express();
var server = require('http').createServer(app);
require('./config/express')(app);
require('./routes')(app);
// Start server
server.listen(config.port, config.ip, function () {
console.log('Express server listening on %d, in %s mode', config.port, app.get('env'));
});
// Expose app
exports = module.exports = app;
Most of this is directly from the Yeoman Generator Angular-Fullstack and it has a really nice setup!

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