Revisit Checkbox Fields

[dillonredding]

Currently, checkbox fields work similar to HTML.

{
  "type": "checkbox",
  "name": "foo",
  "value": "bar",
  "checked": false
}

In the above Field example, foo=bar will only be sent to the server if checked is truthy. Otherwise, foo is not sent at all (see here). However, this requires clients to understand and utilize the checked extension for submission. I think we should abandon the need for the extension and send the field's value regardless. The checkedness can be tracked elsewhere and used to update the field's value (e.g., to true/false).

Basically, checkbox fields should have the type Field<boolean>.

[SeeSharpCode]

Am I understanding correctly that the field would look like this:

{
  "type": "checkbox",
  "name": "foo",
  "value": false
}

And value=false would be sent to the server?

[dillonredding]

The main difference for this library would be removing the field.checked condition in the default field serializer. Instead of including {field.name}={field.value} or nothing as with HTML, the former would always be included and it would be up to the client what the field value would be when the checkbox is checked vs unchecked. Since it's a checkbox, a boolean probably makes the most sense, but it could technically be any values that make sense in the context of the API.

[SeeSharpCode]

Sounds good. I'm in favor of this change since it will make checkbox field behavior consistent with other field types.