notebook/app/controllers/attribute_fields_controller.rb

# Controller for the Attribute model
class AttributeFieldsController < ContentController

  def destroy
    # Delete this field as usual -- sets @content
    super

    # If the related category is now empty, delete it as well
    related_category = @content.attribute_category
    related_category.destroy if related_category.attribute_fields.empty?
  end

  private

  def initialize_object
    @content = AttributeField.find_or_initialize_by(content_params)
    @content.field_type = 'text_area'

    if @content.attribute_category_id.nil?
      category = current_user.attribute_categories.where(label: content_params[:attribute_category] || content_params[:label]).first_or_initialize.tap do |c|
        c.entity_type = params[:entity_type] || content_params[:entity_type]
        c.save!
      end
      @content.attribute_category_id = category.id
    end

    Mixpanel::Tracker.new(Rails.application.config.mixpanel_token).track(current_user.id, 'created attribute', {
      'content_type': params[:entity_type]
    }) if Rails.env.production?
  end

  def content_deletion_redirect_url
    :back
  end

  def content_creation_redirect_url
    if @content.present?
      category = @content.attribute_category
      attribute_customization_path(content_type: category.entity_type)
    else
      :back
    end
  end

  def successful_response(url, notice)
    respond_to do |format|
      format.html { redirect_to attribute_customization_path(content_type: @content.attribute_category.entity_type), notice: notice }
      format.json { render json: @content || {}, status: :success, notice: notice }
    end
  end

  def content_params
    params.require(:attribute_field).permit(content_param_list)
  end

  def content_param_list
    [
      :universe_id, :user_id,
      :attribute_category,
      :name, :field_type,
      :label, :description,
      :entity_type, :attribute_category_id,
      :hidden
    ]
  end
end