Support multiple values for query params

[sanjayatn]

Support Multiple Values for Query Params. In the wikipedia article for https://en.wikipedia.org/wiki/Query_string it says "While there is no definitive standard, most web frameworks allow multiple values to be associated with a single field (e.g. field1=value1&field1=value2&field2=value3). Many frameworks support this even though it is not the standard. Currently Pistache supports multiple values separated by a comma by default.

This PR adds two enhancements:

1. Transform the multiple value through duplicate param names into a list of values separated by a , to allow the rest of the framework to convert values to std::vector
2. Provide all the param/value pairs received with the request.
3. Add Query update method to replace a value in the Query collection.

[Tachi107]

Hi @sanjayatn, thanks for your patch! Could you please add more information about it (comments etc.)?

[kiplingw]

And rebase too.

[sanjayatn]

@Tachi107 @kiplingw I didn't realized you can see this branch but I love to submit it as a proper PR! Coming up today!

[codecov-commenter]

Codecov Report

Patch coverage: 26.66% and project coverage change: -0.12 :warning:

Comparison is base (a68ad09) 78.48% compared to head (aa6c74a) 78.36%.

:exclamation: Current head aa6c74a differs from pull request most recent head d268fdc. Consider uploading reports for the commit d268fdc to get more accurate results

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Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #1130 +/- ## ========================================== - Coverage 78.48% 78.36% -0.12% ========================================== Files 53 53 Lines 6892 6907 +15 ========================================== + Hits 5409 5413 +4 - Misses 1483 1494 +11 ``` | [Impacted Files](https://codecov.io/gh/pistacheio/pistache/pull/1130?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=None) | Coverage Δ | | |---|---|---| | [include/pistache/http.h](https://codecov.io/gh/pistacheio/pistache/pull/1130?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=None#diff-aW5jbHVkZS9waXN0YWNoZS9odHRwLmg=) | `86.48% <ø> (ø)` | | | [src/common/http.cc](https://codecov.io/gh/pistacheio/pistache/pull/1130?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=None#diff-c3JjL2NvbW1vbi9odHRwLmNj) | `73.57% <26.66%> (-1.09%)` | :arrow_down: |

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[sanjayatn]

@Tachi107 @kiplingw I see two things failing in the checks. Which one should focus on? If you can give me 2 sentence summary of what abidiff / abi step's goal, then I have better idea to fix it.

[kiplingw]

Hey @sanjayatn. For commitlint you can find what it's complaining about here. For abidiff my guess is you may have missed this.

[sanjayatn]

@kiplingw thanks!

[Tachi107]

Hi @sanjayatn, thanks for the added description and sorry for the delayed response.

I'm personally not a fan of multiple query parameters because, as you say, the behaviour is not standardized, and differences in how different software components handle them can be a source of security vulnerabilities, so much that this class of vulnerabilities got a name: "HTTP parameter pollution".

That being said, aligning to what others do is probably fine, as long as the others do sensible stuff.

Could you please add a couple of test cases showing this new behaviour? Thanks!