Form helpers expectations description

[gonzalo-bulnes]

In order to keep focus on valuable features, the form helpers which are expected to be available for forms building should be defined and described here, or in the README.

[gonzalo-bulnes]

Proposal: Polymorphic address association

Given chilean_cities is a Rails engine, it could provide an Address model with a polymorphic belongs_to :addressed, polymorphic: true.

The simpler Address attributes set able to handle any address in Chile seems to be:

- address line 1 (String)
- address line 2 (String)
- city (association, ChileanCities::Comuna)

The form related to that model requires at least a <select> tag to set the association. Since there are 350+ cities, that's not very user-friendly. In a first time, it could be replaced by a Bootstrap typeahead. (Other select latyouts such as ordering the cities by region could be considered later.)

The typical usage of the gem would become:

1. generate the cities seed and run migrations
2. add has_one work_address, as: :addressed to your models
3. add the address(es) to your models forms (should be possible with something like):

form_for :my_model_instance,  do |f|
  # ...
  f.fields_for :work_address do |work_address_form| do
    work_address_form.input :line_one
    work_address_form.input :line_two
    work_address_form.city, collection: ChileanCities::Comuna.all
  end
  # ...
end