Hq.form_fields with `inputs_for` should return nested maps and lists of maps

[sax]

Right now, when nested inputs are produced using inputs_for, the data comes out as follows:

%{
  form: %{
    form_has_one: %{},
    form_has_many_0: %{},
    form_has_many_0_belongs_to: %{}
  }
}

This produces maps that cannot be used when changing or submitting their forms.

It would be utilitarian to produce:

%{
  form: %{
    has_one: %{},
    has_many: [
      %{
        belongs_to: %{}
      }
    ]
  }
}

[eahanson]

I think there are 3 types of form parsing we might want:

1. Return what is currently in the HTML
2. Return what a browser would send to the server (e.g., it wouldn't send un-checked checkboxes or disabled field values)
3. Return what a framework like Phoenix or Rails would return (like the nested form in your example)

Type 3 is the most common, but it has been confusing in the past when someone expected type 2 or type 1.

Type 3 could be called form_fields/0, type 2 could be called form_data/0, and type 1 could be called raw_form_values/0

[sax]

Perhaps HtmlQuery.form_fields could take a second argument, which would be the mode. Then we could default it to either the most common or the most expected version.

[eahanson]

I like the single function with a “mode” parameter.

I started a branch a while back but didn’t get too far. Some of it, particularly some of the tests, may be valuable. main...form-updates