actionpack/lib/action_controller/form_builder.rb
# frozen_string_literal: true
# :markup: markdown
module ActionController
# # Action Controller Form Builder
#
# Override the default form builder for all views rendered by this controller
# and any of its descendants. Accepts a subclass of
# ActionView::Helpers::FormBuilder.
#
# For example, given a form builder:
#
# class AdminFormBuilder < ActionView::Helpers::FormBuilder
# def special_field(name)
# end
# end
#
# The controller specifies a form builder as its default:
#
# class AdminAreaController < ApplicationController
# default_form_builder AdminFormBuilder
# end
#
# Then in the view any form using `form_for` will be an instance of the
# specified form builder:
#
# <%= form_for(@instance) do |builder| %>
# <%= builder.special_field(:name) %>
# <% end %>
module FormBuilder
extend ActiveSupport::Concern
included do
class_attribute :_default_form_builder, instance_accessor: false
end
module ClassMethods
# Set the form builder to be used as the default for all forms in the views
# rendered by this controller and its subclasses.
#
# #### Parameters
# * `builder` - Default form builder, an instance of
# ActionView::Helpers::FormBuilder
def default_form_builder(builder)
self._default_form_builder = builder
end
end
# Default form builder for the controller
def default_form_builder
self.class._default_form_builder
end
end
end