CODEWITHSUNDEEP
node.jsexpress
Thomas Hunter II
Thomas Hunter II

Reputation: 5181

Modifying Express.js Request Object

In express.js, I would like to provide an additional attribute on the request object for each of my URI listeners. This would provide the protocol, hostname, and port number. For example:

app.get('/users/:id', function(req, res) {
  console.log(req.root); // https://12.34.56.78:1324/
});

I could of course concatenate req.protocol, req.host, and somehow pass around the port number (seems to be missing from the req object) for each one of my URI listeners, but I'd like to be able to do it in a way that all of them could access this information.

Also, the hostname can vary between request (the machine has multiple interfaces) so I can't just concatenate this string when the application launches.

The goal is to provide URI's to the consumer which point to further resources in this API.

Is there some sort of way to tell Express that I want req objects to have this additional information? Is there a better way to do this than what I'm outlining?

Upvotes: 46

Views: 66953

Answers (5)

apflieger
apflieger

Reputation: 1231

Express was designed to support this in the response object, not the request. The response object support custom variables in res.locals. See http://expressjs.com/en/4x/api.html#res.locals

This is particularly useful for typescript users. The locals property is typed Record<string, any>

Upvotes: 1

TJ Holowaychuk
TJ Holowaychuk

Reputation: 649

You can extend the express.request prototype.

Upvotes: 37

Jonathan Lonowski
Jonathan Lonowski

Reputation: 123423

You can add a custom middleware that sets the property for each request:

app.use(function (req, res, next) {
    req.root = req.protocol + '://' + req.get('host') + '/';
    next();
});

Using req.get to obtain the Host header, which should include the port if it was needed.

Just be sure to add it before:

app.use(app.router);

Upvotes: 79

Mattias
Mattias

Reputation: 9471

You can use a middleware. Add this to your app.configure block:

app.use(function (req, res, next) {
  req.root = 'WHAT YOU WANT';
  next();
});

Every request will go tough this function, and afterwards go to the right url-block thanks to next().

Upvotes: 4

DeadAlready
DeadAlready

Reputation: 3008

The best way to modify the request object is to add your own middleware function before the app.router declaration.

    app.use(function(req, res, next){
      // Edit request object here
      req.root = 'Whatever I want';
      next();
    });
    app.use(app.router);

This will modify the request object and every route will be able to access req.root property, so 

    app.get('/',function(req, res, next){
      console.log(req.root); // will print "Whatever I want";
    });

Upvotes: 9

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