Proposal: Another type of `arrayFormat`

[d-asensio]

Hi,

I think that would be good to add another type of arrayFormat in both stringify and parse methods for joining array values with a comma.

The reason of my proposal is that with the OpenAPI 3 specification they allow to do that (see: OpenAPI spec > fixed fields style and explode fields).

I can understand that you want to keep the functionality of this package as standard as possible (based in the HTTP spec) but I think that would be a nice feature for those who use this package to build API-related url query strings.

Of course this would only provide a code style improvement, since you can reach the same result with the current functionality by doing something like this:

queryString.stringify({
    foo: [1,2,3].join(`,`),
    bar: ['a','b','c'].join(`,`)
});

But I think is much more clear to do it this way:

queryString.stringify({
    foo: [1,2,3],
    bar: ['a','b','c']
}, { arrayFormat: "noExplode"});

I would like to submit a PR if you accept my proposal.

PD:
Another option could be to allow the user build its own arrayFormatter by passing a callback instead of a string... Maybe?

Looking forward your feedback!!

[chacestew]

I second the need for this.

Currently when handling dynamic requests we need to iterate over the payload and manually join any arrays before passing them to query-string. This defeats the purpose of using a library to abstract away the URL parsing.

[sindresorhus]

PR welcome. Should include docs and tests :)

[yadielar]

+1 from me as well. I actually submitted issue #122 and PR #124 trying to solve a problem related to this issue.

In my scenario, I'm working with an API url that uses the following array format for tags:

tags=postal%20office,burger%2C%20fries%20and%20coke

And I was resorting to something similar to what @d-asensio describes:

let tags = ['postal office', 'burger, fries and coke'];

let params = {
  tags: tags.map(t => encodeURIComponent(t)).join(',') // encode manually
}

let qs = queryString.stringify(params, { encode: false }); // disable encoding

This worked just fine for creating the query string, but I stumbled into limitations when parsing it. Since the API url allows commas inside tags, and those are decoded automatically by parse, I was getting the following:

let params = queryString.parse(qs)
// => { tags: 'postal office,burger,fries and coke' }

let tags = params.tags.split(',');
// => ['postal office', 'burger', 'fries and coke'

Therefore my issue suggesting adding the decode option to parse as well, which lets me do:

let params = queryString.parse(qs, { decode: false })
// => { tags: 'postal%20office,burger%2C%20fries%20and%20coke' }

let tags = params.tags.split(',').map(t => decodeURIComponent(t));
// => ['postal office', 'burger, fries and coke'

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I share my specific scenario here in case it might bring more light to the usefulness of this issue and #122.

[dalgleish]

I think this issue was addressed with #167