app.use(path, router) matches but does not extract named parameters in path

[phildow]

I am trying to separate routes into individual files with the app.use('/', router) pattern employed by default in an express initialized application. For example:

var users = require('./routes/users');
// ...
app.use('/users', users);

I've added a posts router for a blog, which works fine:

var posts = require('./routes/posts');
// ...
app.use('/posts', posts);

However, I'm now adding comments subroutes on posts. I need to employ a named parameter in the path supplied to app.use so that I can identify the post in addition to the comment:

var comments = require('./routes/comments');
// ...
app.use('/posts/:pid/comments', comments);

The routes/comments.js file looks like:

var express = require('express');
var router = express.Router();

router.get('/', function(req, res) {
  res.send('all comments + ', req.params.pid);
});

// ...

A path such as /posts/1/comments/34 correctly matches and the callback in router/comments.js is executed, but req.params.pid is undefined.

It looks like this is intentional behavior after posting to stack overflow. I understand one workaround is to include the additional path matching in routes/posts.js itself and point the callbacks to a separate routes/comment.js file, but then I cannot use parallel router.verb constructions there.

I've also found that I can simply use /posts again as the base path when referencing the routers from the main application file:

app.use('/posts', posts);
app.use('/posts', comments);

and rely on priority matching and on more targeted matching in routes/comment.js, but that solution leads to ambiguity considering the above code.

May I suggest supporting this as a feature request? It allows for parallel code constructions in the two routes files and would behave intuitively.

[dougwilson]

The feature exists now but is currently op-in. Just declare your comments.js router like this:

var router = express.Router({ mergeParams: true });

You need to use express 4.5.0 or higher.

[phildow]

Very cool. Thank you for the prompt reply!