Express 4: How to catch param in dynamic route structured like file name?

Question

I'm trying to use Express 4 route endpoint that has part of the route in the file URL part - file name. It's used for dynamic generated image. I think it's best described by example...

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What I have right now

Right now I have something like this in my routes:

app.get('/api/listing/:id/cover.png', viewListingImage)

And e.g. this URL http://localhost:9500/api/listing/750/cover.png matches listing with id 750.

Expectations

What I would like to have is URL which last part is a filename with listing id in it. So I can quickly save it locally with that filename. E.g.

http://localhost:9540/api/listing/750-cover.png

So basically, I'd like to just replace forward slash with a hyphen.

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Tried some RegEx magic, but had not luck. Thanks for any help!

Answer 1

You can use a regex in the route:

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

// match /api/listing/ddd-filename
// where ddd is a series of digits
app.get(/\/api\/listing\/(\d+)-([^\/]+)/, function(req, res) {
    console.log(req.params);
    res.send("hello");
});

app.listen(80);

Then, if you request a URL such as /api/listing/20-cover.png, you will find that in the request handler:

req.params[0] === '20'
req.params[1] === 'cover.png';

Capture groups in the regex are put into req.params as described here.

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As I said in my comments, you could also just do:

app.get('/api/listing/:filename', function(req, res) {
    // parse req.params.filename yourself here
});