# Idea.joins(content_type: :custom_attributes)
#  ideas com tipo de conteudo que tem atributo customizavel
#
# Idea.left_joins(:custom_attribute_values).where( idea_custom_attribute_values: {id: nil}).select(:id)
#  id das ideas sem idea_custom_attributes
#
ideas = Idea.joins(content_type: :custom_attributes).where(id: Idea.left_joins(:custom_attribute_values).where( idea_custom_attribute_values: {id: nil}).select(:id)).distinct

ideas.each do |idea|
  content_type = idea.content_type

  content_type.custom_attributes.pluck(:id).each do |id|
    new_attribute = idea.custom_attribute_values.new(content_type_attribute_id: id, custom_value: "")
    new_attribute.save(validate: false)
  end
end