How to render ActionText Attachments in Plain Text

ActionText supports custom attachments using Signed Global IDs. We can use this to embed any database record in Rails such as @mentions for users.

For HTML, Rails will use the to_partial_path to render the HTML template for the attachment. For a user, this would be app/views/users/_user.html.erb.

With Plain Text output, Rails will default to the caption specified on the attachable. Typically, this is nil because we don't need a caption for an @mention.

By defining the attachable_plain_text_representation method, we can specify the default value for the plain text ActionText output.

class User
  include ActionText::Attachable

  # When ActionText rendering mentions in plain text
  def attachable_plain_text_representation(caption = nil)
    caption || name
  end

And that's it! Simply render your ActionText content as plain text and it will use this method for rendering.