Rails email action text attachment link_to not showing

Question

After implementing @mentions to Article models has_rich_text, everything works fine but when I try to send these articles as an email, the mentions fail to render right. I see sgid and content, via the inspector but the html just renders a "☒" for the @mentions.

The rails mailer preview shows everything fine, i.e. the mention renders correctly. However, in production it fails to render correctly.

EDIT: After getting some sleep and revisitng the docs I realized that link_to wont work per the docs:

As the :host usually is consistent across the application you can configure it globally in config/application.rb:

config.action_mailer.default_url_options = { host: 'example.com' }

Because of this behavior, you cannot use any of the *_path helpers inside of an email. Instead, you will need to use the associated *_url helper. For example instead of using

<%= link_to 'welcome', welcome_path %>

You will need to use:

<%= link_to 'welcome', welcome_url %>

By using the full URL, your links will now work in your emails.

Need to implement and find out, will update. Reading the docs it seems that Passing in the Active Record model does not work:

More concise yet, when name is an Active Record model that defines a to_s method returning a default value or a model instance attribute

link_to @profile
# => <a href="http://www.example.com/profiles/1">Eileen</a>

therefore need to provide the url also.

Any ideas why this would be/how to fix?

Production:

<action-text-attachment sgid="eyJfcmFpbHMiOnspJaXhuYVdRNkx5OWhjRE12VFhWelkyeGxMekUyUDJWNGNkZWQT09IiwiZXhwIjpudWxsLCJwdXIiOiJhdHRhY2hhYmxlIn19--31217260f33fc8fce3243" content-type="application/octet-stream" content="<a data-turbo-frame=&quot;_top&quot; data-class=&quot;description&quot; target=&quot;_blank&quot; href=&quot;/gadgets/muscles/triceps-brachii&quot;>
        Triceps Brachii
</a>">☒</action-text-attachment>

This just creates an "☒" as you can see.

Dev:

<action-text-attachment sgid="eyJfcmFpbHMiOnsibWVzc2FnZSI6IkJBaEpJaTFuYVdRNkx5OWhjR1Y0TFcxdmNuUDJsdUJqb0dSVlE9IiwiZXhwIjhdHRhY2hhYmxlIn19--391d3670aff9" content-type="application/octet-stream" content="    <a data-turbo-frame=&quot;_top&quot; data-class=&quot;description&quot; target=&quot;_blank&quot; href=&quot;/gadgets/muscles/abductor-hallucis&quot;>
        Abductor Hallucis
</a>">    <a href="/gadgets/muscles/abductor-hallucis">
        Abductor Hallucis
</a></action-text-attachment>

Which creates a link_to for Abductor Hallucis.

For the site to render the content inside ActionText/Trix, I have the following:

_exercise_mention.html.erb:

<%= link_to exercise, data: { turbo_frame: "_top", class: "description" }, target: :_blank do %>
    <%= exercise.name.humanize.titleize %>
<% end %>

_exercise_mention.jbuilder:

json.extract! exercise, :id, :name

json.sgid exercise.attachable_sgid
json.content render(partial: "exercises/exercise_mention", locals: { exercise: exercise }, formats: [:html])

Exercise model:

class Exercise < ApplicationRecord
    include ActionText::Attachable
......
    #show mentions Article
    def to_trix_content_attachment_partial_path
        "exercises/exercise_mention"
    end
    
    #edit mentions Article
    def to_attachable_partial_path
        "exercises/exercise_mention"
    end
end