Tony Messias

If the app key changed, the locator wouldn't be able to verify the SGID, so that would return null. I think you'd need to create a new verifier that still uses the previous key, so something like:

GlobalID::Locator.locate_signed(
  node.attributes['sgid'].value,
  verifier: Verifier.new(oldVerifierHash),
  for: "attachable"
)

Then you could use the replace method from the Fragment and do something like:

ActionText::RichText.where.not(body: nil).find_each do |trix|
  next unless trix.embeds.size.positive?

  trix.update_column :body, trix.body.fragment.replace("action-text-attachment").each do |node|
    return ActionText::Attachment.from_attachable(
      GlobalID::Locator.locate_signed(
        node.attributes['sgid'].value,
        verifier: Verifier.new(oldVerifierHash),
        for: "attachable"
      ),
      node.attributes
    )
  end.to_s
end

Sorry, this is pseudo-code, I don't write Ruby that often. This code was actually a port of a piece of code I wrote using my PHP-port of the ActionText gem, here's a gist:

https://gist.github.com/tonysm/36d2c413b479b29741af9613fb9808ad

There might be better ways, this was just my first take on solving it.