Paperclip input for Simple Form

paperclip_file_input.rb

class PaperclipFileInput < SimpleForm::Inputs::FileInput
  def input
    value = object.persisted? && object.reload.send(attribute_name)

    current_image_tag = if value.present? && value.content_type =~ /image/
      template.image_tag(value.url, :alt => "#{attribute_name}_image")
    else
      ""
    end

    current_image_tag + super
  end

  def errors_on_attribute
    object.errors[attribute_name] +
    object.errors["#{attribute_name}_file_name"] +
    object.errors["#{attribute_name}_content_type"] +
    object.errors["#{attribute_name}_file_size"]
  end
end