FWIW, I needed to swap out the default qs serializer in here for qs as well. This would be a valuable feature IMO.

On node 10.6, I just tried using the built-in querystring API for the paramsSerializer, and it seems to encode the array correctly.

https://nodejs.org/api/querystring.html#querystring_querystring_stringify_obj_sep_eq_options

If there is no standard/RFC that defines this, why was it decided that [] should be used? I understand a custom paramsSerializer can be implemented, but the current implementation shouldn't be opinionated.

I used this solution, unfortunately it requires an additional package for something that perhaps can be fixed with a simple toggle config.
#559 (comment)

up

Also would like to see a better solution for this.

Really understand that users want everything out-of-box. But axios has its own design principle, which means simple and focused. Hope someone can list where those two formats come from, and let's choose the more standard one.

the better solution is to use JSON arrays with application/json content-type.
Especially, new servers (no matter typed or not) should use more advanced (than form enctype) exchange..

On this I don't think this should be implement as mentioned previously if you'd like to use another format, you can set a custom paramsSerializer as follows:

axios.defaults.paramsSerializer: function(params) {
  // return a query string
}

Using the qs library:

axios.defaults.paramsSerializer: function(params) {
  return qs.stringify(params, { indices: false }); // param=value1&param=value2
}

I have a problem with the by @jasonsaayman mentioned approach...

param=value1&param=value2 on C# backend correctly maps to param[] array. but param=value1 does not!

Not sure yet how to solve this. Anyone?

Update: Nevermind. While debugging I figured out the actual issue was something completely different ^^

On this I don't think this should be implement as mentioned previously if you'd like to use another format, you can set a custom paramsSerializer as follows:

I'm not sure I fully agree. There is nothing in the specification that says that these parameters should be suffixed with brackets (neither is there anything that says that it shouldn't), which makes this very opinionated (as mentioned previously).

Fixing this by adding the qs package works, but it feels like an unnecessary thing to do when it would be a very simple configuration flag in Axios itself. The fewer dependencies the better, in my view.

I could rely on the native Node.js querystring package, but there's two issues with that:

• I'm using TypeScript, and the native function does not accept any, which is what Axios "provides".
• It's deprecated in favor of the URLSearchParams API, which also does not seem to work well with an any object.

I could also replicate the entire function that Axios has by default, but that also feels like a very inconvenient way of handling this.

Could you consider re-opening this issue? 😃

I already had tried something like this: #1565

But same response: use qs.

For those like me that are just now stumbling upon this thread, the bracketless format can now be configured:

axios.defaults.paramsSerializer = {
  indexes: null,
};

need to check if this in the docs @DavidJDallas

closing due to being very stale, if this is still relevant please open a new issue