Formtastic check boxes with awesome_nested_set

check_boxes_input.rb

# put this file in any autoloaded path on rails app. HINT: app/inputs/check_boxes_input.rb 

class CheckBoxesInput < Formtastic::Inputs::CheckBoxesInput
    
  def to_html
    unless options[:nested_set]
      super
    else
      nested_wrapping(options)
    end
  end
  
  def nested_wrapping(options)
    choices_wrapping do
      legend_html <<
      hidden_field_for_all <<
      choices_group_wrapping do
        html_template_for_nested_set(options)
      end
    end
  end
  
  def html_template_for_nested_set(options)
    options[:collection].map{|menu|
      html_for_nested(menu)
    }.join("\n").html_safe
  end
  
  def html_for_nested(menu, from_nested=false)
    choice = [menu.name , menu.id]
    first_wrap = choice_wrapping(choice_wrapping_html_options(choice)) do
      nested = from_nested ? "" : sub_children(menu)
      choice_html(choice) << nested
    end 
  end

  def sub_children(menu)
    template.content_tag( :ul,
     menu.children.collect do |child|
       html_for_nested(child, true)
     end.join("\n").html_safe, 
     {:style=>"margin-left:20px", :class=>"sub_item-#{menu.id} sub-item"}
    )  unless menu.leaf?
  end
  
end

check_boxes_input_usage.md

model

class Category < ActiveRecord::Base
   acts_as_nested_set
....

View

= f.input :categories, :as=>:check_boxes, :collection=>Category.where(["parent_id is NULL"]) , :nested_set=>true