angular_form_builder.rb

# Adds ng-model attrs to all formatastic inputs
# based on ActiveModel naming conventions
class AngularFormBuilder < Formtastic::FormBuilder

  # Almost exact dupilicate of the formtastic input method
  # but thhe magick is in the extends :) (Line 13)
  def input(method, options = {})
    method = method.to_sym if method.is_a?(String)
    options = options.dup
    options[:as] ||= default_input_type(method, options)

    klass = input_class(options[:as])

    klass.new(self, template, @object, @object_name, method, options).extend(NgAttrs).to_html
  end

  private

  module NgAttrs
    def input_html_options
      {
        'ng-model' => ng_model_name
      }.merge(super)
    end

    def ng_model_name
      [
        builder.custom_namespace,
        object_name.to_s.split(/\[|\]/),
        dom_index,
        association_primary_key || sanitized_method_name
      ].flatten.reject { |x| x.blank? }.join('.')
    end
  end
end

application_helper.rb

module ApplicationHelper

  def angular_form_for(record_or_name_or_array, *args, &proc)
    options = args.extract_options!
    options[:builder] ||= AngularFormBuilder
    semantic_form_for(record_or_name_or_array, *(args << options), &proc)
  end

  # snip...
end