在ActiveAdmin中的before_filter中填充表单的集合

Question

I am trying to populate a collection (@displayable_collection) to select from in my form
(this is a simplified version of what will eventually go into @displayable_collection

Here is my code... but it isn't working ..... what am I doing wrong?

controller do
  before_filter :populate_collection, :only => [:new, :edit]

  private
  def populate_collection
    @displayable_collection = ArtItem.all.map{ |item| [item.to_s, "#{item.class}_#{item.id}"]}
  end
end

form do |f|
  f.inputs 'Details' do
    f.input :project
    f.input :name
  end

  f.inputs 'Display Items' do
    f.has_many :display_items do |item|
      item.input :displayable_combined_fields, :collection => @displayable_collection
      item.input :location, :input_html => {:selected => location.id}
      item.input :height
      item.input :width
      item.input :depth
    end
  end
  f.actions
end

Answer 1

So the Answer is that you reference the instance variable as a helper method. I know it sounds weird, but it works.

Documented here: https://github.com/gregbell/active_admin/issues/2298

controller do
  before_filter :populate_collection, :only => [:new, :edit]

  private
  def populate_collection
    @displayable_collection = ArtItem.all.map{ |item| [item.to_s, "#{item.class}_#{item.id}"]}
  end
end

form do |f|
  f.inputs 'Details' do
    f.input :project
    f.input :name
  end

  f.inputs 'Display Items' do
    f.has_many :display_items do |item|
      item.input :displayable_combined_fields, :collection => displayable_collection
      item.input :location, :input_html => {:selected => location.id}
      item.input :height
      item.input :width
      item.input :depth
    end
  end
  f.actions
end