Multiple query parameters with same name

Question

I want to know how does EXPRESS parse multiple query parameters with the same name; I couldn't find any useful reference anywhere. I want to know specifically about EXPRESS, how is it going to treat this URL www.example.com/page?id=1&id=2&id=3.....id=n

Does this answer your question? [Correct way to pass multiple values for same parameter name in GET request](https://stackoverflow.com/questions/24059773/correct-way-to-pass-multiple-values-for-same-parameter-name-in-get-request) — Rohit Ambre, Jun 26 '20 at 06:22
No, it talks about which method is better, not how they work. Also, I think each framework has its own ways to parse things, especially for such corner-cases and that's why I mentioned EXPRESS. I saw that before asking. Thanks anyway! — hakiki_makato, Jun 26 '20 at 06:28
QueryParser in Express is configurable, the default configuration ("extended") uses [qs](https://www.npmjs.org/package/qs) to parse query strings, the simple mode uses Node’s native query parser [querystring](https://nodejs.org/api/querystring.html), and you can also define your own parser. I couldn't find anything from the linked documentations concerning double names, but you can test it. — Teemu, Jun 26 '20 at 06:53
Hey @Teemu, thanks for replying, as you mentioned, I've found some correlations. From what I've understood, It's storing them in an array which in my opinion is a good way for bypassing filters for local file inclusion. I just want some concrete documentation or RFC section supporting some similar argument. — hakiki_makato, Jun 26 '20 at 07:25
As Eduardo has stated in the [suggested dup](https://stackoverflow.com/a/24728298/1169519), "_there is no defined standard_", you've to examine the documentation of the implementations, which in these two cases don't seem to contain the wanted information. Hence the only way to find out is testing ... — Teemu, Jun 26 '20 at 07:46

score 2 · Answer 1 · answered Nov 10 '20 at 16:06

You can use the usual req.query. Whenever there's multiple query parameters with the same name, req.query[paramName] will return an array instead of the value. So in your case:


app.get("/page", (req, res) => {
    const { id } = req.query
    console.log("ID is "+ id) 
});

// GET www.example.com/page?id=1&id=2&id=3
// ID is ["1", "2", "3"]

// GET www.example.com/page?id=12345
// ID is 12345

Multiple query parameters with same name

1 Answers1