Support readonly for all fields

[gmazzamuto]

Support :readonly option for all fields.

The :readonly field option, being shared among all fields, has been moved to the @config_schema of Backpex.Field. This should not be a breaking change.

Example of readonly fields:

[Flo0807]

Suggested change

	attr :readonly, :boolean, default: false
	attr :readonly, :boolean, default: false, doc: "whether the dropdown is readonly"

[Flo0807]

Suggested change

	assigns =
	if Map.has_key?(assigns.rest, :disabled) do
	assigns
	else
	put_in(assigns, [:rest, :disabled], Map.get(assigns.rest, :readonly) || false)
	end

Why do we want to set disabled based on the readonly attribute? If you want to set the input to disabled, you should explicitly pass the disabled attribute, in my opinion.

[Flo0807]

See https://github.com/naymspace/backpex/blob/0.16.3/lib/backpex/fields/text.ex#L58

I noticed that we do not set dsiabled in every field (e.g. Backpex.Fields.Select)

[gmazzamuto]

yeah you're right, I'll review your comments to this PR asap (some time has passed and I can't remember right now). Anyways I was confused by the fact that in Backpex almost all fields have

<BackpexForm.input
  ...
  readonly={@readonly}
  disabled={@readonly}
>

Do you think it makes sense to have two separate options, :readonly and :disabled? After all, they serve different purposes. If that's the case I can work on that and add the :disabled option to Backpex.Field.

[Flo0807]

See https://github.com/naymspace/backpex/pull/1677/files#r2591617008

[Flo0807]

This looks complicated. Can't we just add additional classes in the markup in case the dropdown is readonly?

[gmazzamuto]

Here is why. This is how the dropdown is rendered with the code above:

---

Whereas this code:

    trigger_class =
      if assigns.readonly do
        ["cursor-not-allowed bg-base-200"] ++ trigger_class
      else
        trigger_class
      end

results in this, and the field can be even highlighted on mouse click (although the dropdown does not open):

[Flo0807]

undefined attribute "readonly" for component Backpex.HTML.Form.multi_select/1

[Flo0807]

Suggested change

	attr :readonly, :boolean, default: false
	attr :readonly, :boolean, default: false, doc: "whether the dropdown is readonly"

[Flo0807]

For which cases do we need this?

And can we simplify the if-condition?

Suggested change

	assigns =
	if assigns[:readonly] == true do
	assigns
	else
	assign(assigns, :readonly, Backpex.Field.readonly?(field_options, assigns))
	end
	assigns =
	if assigns[:readonly] do
	assigns
	else
	assign(assigns, :readonly, Backpex.Field.readonly?(field_options, assigns))
	end

[gmazzamuto]

Sure, the if condition can be simplified.

The reason for this code is because the :readonly assign is not always defined when calling the callback Backpex.Field.render_form/1 and also to allow individual fields in Backpex.Fields.InlineCRUD to be set readonly when the parent InlineCRUD field is not readonly. I will add a comment in the code to clarify this.