I'm trying to understand how to use an application-level middleware (or at least usually used like this) like cookie-parser on route-level and conditionally.
I tried something like:
const myMiddleware = (req, res, next) => {
if (myCondition) {
return cookieParser();
} else {
next();
}
}
app.use('/admin', myMiddleware, (req, res) => {
res.sendStatus(401)
})
But it's not working, the request will be just stuck.
Is this possible?
Traditional cookie-parser implementation:
app.use(cookieParser())
cookieParser() returns a middleware function, i.e. a function that takes in req, res, next as arguments. You just have to pass it the arguments:
const cookieParserMiddleware = cookieParser();
const myMiddleware = (req, res, next) => {
if (myCondition) {
return cookieParserMiddleware(req, res, next);
}
next();
};
app.use("/admin", myMiddleware, (req, res) => {
res.sendStatus(401);
});
Notice that I'm creating the cookieParser middleware outside myMiddleware - technically we could also just do return cookieParser()(req, res, next) but recreating the same middleware again and again on every request would be wasteful.
I've also removed the else since the if block returns from the function (guard clause).
Related
I'm working on an API that has routes like this (all POST requests)
/friends?d=onlineFriends
/friends?d=offlineFriends
and on...
and this is how it's handled:
server.js
app.post("/friends", (req, res, next) => {
let d = req.query.d
let path "./funcs/" + d + ".js"
return require(path)(req, res, next)
})
./funcs/onlineFriends.js
module.exports = (req, res, next) => {
return res.sendStatus(200)
}
But the thing is, I want to use different middlewares per func, with the code above if I wanted to use a middleware it would apply to all funcs because you'd have to put it in app.post part.
I've tried following:
module.exports = (req, res, next) => {
middleware(req, res, next)
return res.sendStatus(200)
}
but of course it results in Cannot set headers after they are sent to the client.
I know you might ask "Why not use a router like /friends/online", I really can't change the client and this is how I must do it.
If you have middlewares a, b and c, you can dynamically choose a combination of them and use that to handle the request:
app.post("/friends", function(req, res, next) {
var middleware;
switch (req.query.d) {
case "a": middleware = [a, c]; break;
case "b": middleware = [b]; break;
default: return next();
}
express.Router().use(middleware)(req, res, next);
});
I am using express with a pattern like this :
app = express();
router = express.Router();
router.use((req, res, next) => {
console.log("my middleware before");
next();
});
router.get('/foo', (req, res, next) => {
console.log("My route");
res.send("<h1>Hello</h1>")
next();
});
router.use((req, res, next) => {
console.log("my middleware after");
});
app.use("/", router);
app.get("*", (req, res, next) => {
console.log("page not found");
throw new Error("Not Found");
});
app.use((err, req, res, next) => {
console.log("Error occure");
res.send("<h1>Error</h1>");
});
app.listen(3000);
When I request '/foo' I would like to have
> my middleware before
> My route
> my middleware after
<h1>Hello</h1>
And when I request anything else :
> page not found
> Error occure
<h1>Error</h1>
But the page not found route is executed in each case, even if route '/foo' is done.
How can I get it working ?
When I run your code, I do not get the output you show, so something about your real code is apparently different than what you show in your question.
I do get a slightly confusing output and that happens because the browser sends both the /foo request and a /favicon.ico request. When I run it, the /foo request generates the desired output. The /favicon.ico request generates some middleware output and then gets stuck in the router.
If you filter out the /favicon.ico route (so that it doesn't confuse things) by adding this as the first route:
app.get("/favicon.ico", (req, res) => {
res.sendStatus(404);
});
Then, I get exactly this output in the server logs when I request /foo:
my middleware before
My route
my middleware after
Which is exactly what you asked for.
There is, however, a general problem with this:
router.use((req, res, next) => {
console.log("my middleware after");
});
Because it will catch and hang any legit requests that haven't yet had a response sent. You can't really code it that way unless you only don't call next() if a response has already been sent.
As a bit of a hack, you could do this:
router.use((req, res, next) => {
console.log("my middleware after");
// if response hasn't yet been sent, continue routing
if (!res.headersSent) {
next();
}
});
But, there is probably a better way to solve whatever problem you're actually trying to solve. If, in the future, you describe your real problem rather than a problem you have with your solution, then you allow people to offer a wider range of solutions to your real problem including things you haven't even thought of to try. As your question is written right now, we're stuck down the solution path you followed and don't know what the original problem was. That is, by the way, referred to as an XY Problem.
Do this
app = express();
router = express.Router();
router.use((req, res, next) => {
console.log("my middleware before");
next();
});
router.get('/foo', (req, res, next) => {
// use locals to record the fact we have a match
res.locals.hasMatch = true
console.log("My route");
res.send("<h1>Hello</h1>")
next();
});
router.use((req, res, next) => {
console.log("my middleware after");
});
app.use("/", router);
app.get("*", (req, res, next) => {
console.log("page not found");
throw new Error("Not Found");
});
app.use((err, req, res, next) => {
// check locals to see if we have a match
if (!res.locals.hasMatch) {
console.log("Error occure");
res.send("<h1>Error</h1>");
}
});
app.listen(3000);
You can utilize middlewares and even nest them.
You can implement it like this:
Middlewares
const before = (req, res, next) => {
console.log("my middleware before");
next(); // Supply next() so that it will proceed to the next call,
// in our case, since this is supplied inside the router /foo, after this runs, it will proceed to the next middleware
};
const after = (req, res, next) => {
console.log("my middleware after");
};
Route
// Supply "before" middleware on 2nd argument to run it first when this route is called
router.get('/foo', before, (req, res, next) => {
console.log("My route");
res.send("<h1>Hello</h1>");
next(); // Call next() to proceed to the next middleware, or in "after" middleware
}, after); // Supply the "after" middleware
Once ran, it will proceed with this desired result sequence:
> my middleware before
> My route
> my middleware after
Unmatched Routes Handler
Instead of this
app.get("*", (req, res, next) => {
console.log("page not found");
throw new Error("Not Found");
});
You can implement it like this instead, this is after your app.use("/", router); -- This will handle your unmatched routes:
Sources:
https://stackoverflow.com/a/44540743/6891406
https://stackoverflow.com/a/16637812/6891406
app.use((req, res, next) => {
console.log("page not found");
res.json({ error: 'Page not Found' })
});
This is my code when.
I am hitting put API it is executing middleware 3 times but it should execute for put API only.
app.use('/api/user', MiddlewareFun);
app.get('/api/user', (req, res) => {
//do something
});
app.use('/api/user', MiddlewareFun);
app.post('/api/user', (req, res) => {
//do something
});
app.use('/api/user', MiddlewareFun);
app.put('/api/user', (req, res) => {
//do something
});
please don't say use like this.
app.put('/api/user', MiddlewareFun, (req, res) => {
//do something
});
Well, it's happening, because you've made it to. If you want the middleware, to be executed at only selected method, you have to specify it. For example:
Instead of doing:
app.use('/api/user', MiddlewareFun)
app.put('/api/user', (req, res) => {
//do something
})
replace use method with put. As you'd bind regular route:
app.put('/api/user', MiddlewareFun)
app.put('/api/user', (req, res) => {
//do something
})
Also, one more thing. You don't have to duplicate your middleware call before every route declaration. If you want to apply a middleware to your whole router, you can use .use() (as you did), or .all(); which will result in the same behavior.
The middlewares in Express are binded to app or to router.
The solution to yuur problem is to check the method of the request object at the middleware
let MiddlewareFun = function (req, res, next) {
if (req.method === 'PUT') {
// do something
}
next()
}
app.use('/api/user', MiddlewareFun);
The answer is, You need to write express middleware which is part of your app or router. You can write as many middlewares you want, but in your case you just need it only once and here is the implementation of that.
const MiddlewareFun = function(req, res, next) {
// req is object which consist of information about request made.
// From req object you can get method name which is called.
if(req.method.toLowerString() === 'put') {
// your logic goes here
}
next();
}
app.use('/api/user', MiddlewareFun);
app.get('/api/user', (req, res) => {
//do something
});
app.post('/api/user', (req, res) => {
//do something
});
app.put('/api/user', (req, res) => {
//do something
});
what I want it to do.
router.post('/xxxx', authorize , xxxx);
function authorize(req, res, next)
{
if(xxx)
res.send(500);
else
next();
}
I want to check for session in each route.
But since the routers are written in this way.
router.route('/xxx/xxxx').post(function(req, res) {
// blah lah here...
//
});
So how can I set up a middleware that will check for session and I wanted to make things a bit more generic and wanted to have a single authorize function doing a single thing instead of checking in every request.Any suggestions.
Define a middlware function before you define / include your routes, this will avoid you checking for a valid session in every route. See code below for an example on how to do this.
If some routes are public, i.e. they do not require a user to have a valid session then define these BEFORE you 'use' your middlware function
var app = require("express")();
//This is the middleware function which will be called before any routes get hit which are defined after this point, i.e. in your index.js
app.use(function (req, res, next) {
var authorised = false;
//Here you would check for the user being authenticated
//Unsure how you're actually checking this, so some psuedo code below
if (authorised) {
//Stop the user progressing any further
return res.status(403).send("Unauthorised!");
}
else {
//Carry on with the request chain
next();
}
});
//Define/include your controllers
As per your comment, you have two choices with regards to having this middleware affect only some routes, see two examples below.
Option 1 - Declare your specific routes before the middleware.
app.post("/auth/signup", function (req, res, next) { ... });
app.post("/auth/forgotpassword", function (req, res, next) { ... });
//Any routes defined above this point will not have the middleware executed before they are hit.
app.use(function (req, res, next) {
//Check for session (See the middlware function above)
next();
});
//Any routes defined after this point will have the middlware executed before they get hit
//The middlware function will get hit before this is executed
app.get("/someauthorisedrouter", function (req, res, next) { ... });
Option 2 Define your middlware function somewhere and require it where needed
/middleware.js
module.exports = function (req, res, next) {
//Do your session checking...
next();
};
Now you can require it wherever you want it.
/index.js
var session_check = require("./middleware"),
router = require("express").Router();
//No need to include the middlware on this function
router.post("/signup", function (req, res, next) {...});
//The session middleware will be invoked before the route logic is executed..
router.get("/someprivatecontent", session_check, function (req, res, next) { ... });
module.exports = router;
Hope that gives you a general idea of how you can achieve this feature.
Express routers have a neat use() function that lets you define middleware for all routes. router.use('/xxxxx', authorize); router.post('/xxxx', 'xxxx'); should work.
Middleware:
sampleMiddleware.js
export const verifyUser = (req, res, next) => {
console.log('Verified')
next();
}
Routes
import express from 'express';
import { verifyUser } from './sampleMiddleware.js';
const userRoutes = express.Router();
userRoutes.route('/update').put(verifyUser, async function(){
//write your function heere
});
You've probably gotten the answer you need but I'll still drop this
router.route('/xxx/xxxx').get(authorize, function(req, res) {...});
I am trying to define one global middleware which will work for all routes of my app. I tried some ways but still got some issues.
var _gMDLW = function (req, res, next) {
if(req.route) console.log('Called route ', req.route.path);
next();
}
// Working fine and result on _gMDLW is /route1
app.get('/route1', _gMDLW, function (req, res, next) { return res.sendStatus(200); })
var globalRouter = new express.Router()
// Working fine and result on _gMDLW is /view
globalRouter.route('/view')
.get(_gMDLW, function (req, res, next) { return res.sendStatus(200);})
app.use(globalRouter);
But problem is here
// Error in _gMDLW and getting /list instead of /items/list
var itemRouter = new express.Router()
itemRouter.route('/list')
.get(_gMDLW, function (req, res, next) { return res.sendStatus(200);})
app.use('/items', itemRouter)
Second Question is is there any way to define/add _gMDLW inside app instead of adding in each route something like app.use(_gMDLW) ?
Thank you
You can use app.all() to resolve this issue
Example
app.all('*', _gMDLW);
function _gMDLW(req, res, next) {
if (req.path == '/') return next();// redirect to homepage for guest
next();//authenticated user
}
You can modify it as your requirement