Add Lucky::Params#get_all

[matthewmcgarvey]

Purpose

Fixes #1380
Related luckyframework/avram#408

Description

Allows fetching an array of values from Lucky::Params. This is needed to support things like multi-select inputs, and array columns in Avram::Model.

Checklist

• - An issue already exists detailing the issue/or feature request that this PR fixes
• - All specs are formatted with crystal tool format spec src
• - Inline documentation has been added and/or updated
• - Lucky builds on docker with ./script/setup
• - All builds and specs pass on docker with ./script/test

[matthewmcgarvey]

You might ask, "What about if the user doesn't want to use the key[] pattern?"

I'm open to feedback but I think we're pretty clear in Lucky that we prefer convention with a backdoor and the backdoor in this scenario is to access the params directly: params.from_query.fetch_all("keys")

[jkthorne]

What do you think about this?

Suggested change

	vals = params.fetch_all(key + "[]")
	if vals.any?
	vals
	else
	nil
	end
	params.fetch_all(key + "[]").try &.any?

[matthewmcgarvey]

Doesn't #any? return a boolean? #fetch_all always returns an array, the goal is to return nil if the array is empty

[jwoertink]

For the most part, this looks good. I just have the one concern as far as the API for it goes. Also just to be clear that the intended use is different from the params.many_nested method, right? This is just for supporting raw arrays in params?

[jwoertink]

Sweet! Yeah, this feels pretty good. Thanks for making the change 😃