Hi, I've implemented action-text in our Rails 6 app to get some user-provided text that we put in generated PDFs (prawn). Everything is great except that Trix doesn't support the underline tag.

I've updated ActionText Trix.config.textAttributes to include u as a valid tagName and I've created a custom toolbar that adds a button for underline. The <u> tags are properly getting stored in the database when the form is saved.

I then added Rails::Html::SafeListSanitizer.allowed_tags << "u" to get the rendered show view to stop stripping the <u> tags.

So, everything is great except when re-rendering the editor form, the <u> tags are stripped.

In reading discussions and looking at the code, defining u as a tagName in Trix.config.textAttributes should mean that Trix.HTMLSanitizer includes that tag in the list of allowed attributes, but that isn't happening.

Any ideas on this last step to make a custom textAttribute tag work correctly for a full life-cycle?

Details

• Trix version: Rails 6.0.3
• Browser name and version Chrome latest
• Operating system: Mac OS X