Unsubscribe Link Implementation in Discourse Emails

The following strings are in message_builder.rb - discourse/lib/email/message_builder.rb at 2dae20c05434cdb96f59a996167f77a389169c4d · discourse/discourse · GitHub

unsubscribe_link
unsubscribe_link_and_mail

the default text for both is:

To unsubscribe from these emails, [click here](%{unsubscribe_url}).

Please explain how they work.

Certainly! I’ll examine the message_builder.rb file and explain how the unsubscribe_link and unsubscribe_link_and_mail work. Let’s start by retrieving the content of the file.

GitHub file content

Retrieved content of ["lib/email/message_builder.rb"] 2dae20c05434cdb96f59a996167f77a389169c4d from discourse/discourse@2dae20c05434cdb96f59a996167f77a389169c4d

I apologize for the error in retrieving the file content. It seems there was an issue with the file path format. Let me try again with the correct format.

GitHub file content

Retrieved content of lib/email/message_builder.rb from discourse/discourse@2dae20c05434cdb96f59a996167f77a389169c4d

Thank you for providing the file content. I’ll explain how the unsubscribe_link and unsubscribe_link_and_mail work in the message_builder.rb file.

Both unsubscribe_link and unsubscribe_link_and_mail are used to generate unsubscribe instructions for email notifications. They are part of the email template system in Discourse. Here’s how they work:

1. The default text for both is:
   To unsubscribe from these emails, [click here](%{unsubscribe_url}).

2. The choice between unsubscribe_link and unsubscribe_link_and_mail is determined in the initialize method of the MessageBuilder class:

if @opts[:add_unsubscribe_link]
  unsubscribe_string =
    if @opts[:mailing_list_mode]
      "unsubscribe_mailing_list"
    elsif SiteSetting.unsubscribe_via_email_footer
      "unsubscribe_link_and_mail"
    else
      "unsubscribe_link"
    end
  @template_args[:unsubscribe_instructions] = I18n.t(unsubscribe_string, @template_args)
end

3. The decision is based on the following conditions:

   • If mailing_list_mode is enabled, it uses unsubscribe_mailing_list.
   • If SiteSetting.unsubscribe_via_email_footer is true, it uses unsubscribe_link_and_mail.
   • Otherwise, it uses unsubscribe_link.

4. The chosen unsubscribe string is then translated using I18n.t() and stored in @template_args[:unsubscribe_instructions].

5. The unsubscribe_url is set earlier in the initialize method:

@template_args = {
  # ... other args ...
  user_preferences_url: "#{Discourse.base_url}/my/preferences",
  # ... other args ...
}.merge!(@opts)

6. Later in the code, when building the email headers, the unsubscribe URL is set:

unsubscribe_url =
  @template_args[:unsubscribe_url].presence || @template_args[:user_preferences_url]
result["List-Unsubscribe"] = "<#{unsubscribe_url}>"

7. The unsubscribe instructions are included in both the HTML and text versions of the email:

   • For HTML emails:

     if @template_args[:unsubscribe_instructions].present?
       unsubscribe_instructions =
         PrettyText.cook(@template_args[:unsubscribe_instructions], sanitize: false).html_safe
       html_override.gsub!("%{unsubscribe_instructions}", unsubscribe_instructions)
     else
       html_override.gsub!("%{unsubscribe_instructions}", "")
     end
     

   • For text emails:

     if @template_args[:unsubscribe_instructions].present?
       body << "\n"
       body << @template_args[:unsubscribe_instructions]
     end
     

In summary, unsubscribe_link and unsubscribe_link_and_mail are translation keys that determine the content of the unsubscribe instructions in email notifications. The choice between them depends on the site settings and mailing list mode. The resulting instructions are included in both HTML and text versions of the email, and a proper unsubscribe URL is set in the email headers.