The code is based on what's generated using CKEditor's code generator.
We're doing one minor change to the `Ckeditor::Backend::ActiveStorage`
module; we're assigning the data in a `before_validation` instead of a
`before_save` callback. Validations with `file_validations` didn't work
otherwise; it looks like this backend was written with
`active_storage_validations` in mind [1].
Note we don't need to update the `name` column in the attachments table
because, when using Active Storage, CKEditor uses both `data` (as
attribute accessor) and `storage_data` (as attachment attribute).
[1] https://github.com/galetahub/ckeditor/blob/f9e48420ccb6dc/lib/generators/ckeditor/templates/active_record/active_storage/ckeditor/picture.rb#L4
Since we're going to remove Paperclip and Active Storage doesn't provide
any validations, we have to either write our own validation rules or use
a different gem.
We're using the file_validators gem instead of the
`active_storage_validations` gem because the latter doesn't support
proc/lambda objects in size and content type definitions. We need to use
them because in our case these values depend on settings stored in the
database.
In order to migrate existing files from Paperclip to ActiveStorage, we
need Paperclip to find out the files associated to existing database
records. So we can't simply replace Paperclip with ActiveStorage.
That's why it's usually recommended [1] to first run the migration and
then replace Paperclip with ActiveStorage using two consecutive
deployments.
However, in our case we can't rely on two consecutive deployments
because we have to make an easy process so existing CONSUL installations
don't run into any issues. We can't just release version 1.4.0 and 1.5.0
and day and ask everyone to upgrade twice on the same day.
Instead, we're following a different plan:
* We're going to provide a Rake task (which will require Paperclip) to
migrate existing files
* We still use Paperclip to generate link and image tags
* New files are handled using both Paperclip and ActiveStorage; that
way, when we make the switch, we won't have to migrate them, and in
the meantime they'll be accessible thanks to Paperclip
* After we make the switch, we'll update the `name` column in the active
storage attachments tables in order to remove the `storage_` prefix
Regarding our handling of new files, the exception are cached
attachments. Since those attachments are temporary files used while
submitting a form and we have to delete them afterwards, we're only
handling them with Paperclip. We'll handle these ones in version 1.5.0.
Note the task creating the dev seeds was failing after these changes
with an `ActiveStorage::IntegrityError` exception because we were
opening some files without closing them. If the same file was attached
twice, it failed the second time.
We're solving it by closing the files with `File.open` and a block. Even
though we didn't get any errors, we're doing the same thing in the
`Attachable` concern because it's a good practice to close files after
we're done with them.
Also note we have to change the CKEditor Active Storage code so it's
compatible with Paperclip. In this case, I haven't been able to write a
test to confirm the attachment exists; I was getting the same
`ActiveStorage::IntegrityError` mentioned above.
Finally, we're updating the site customization image controller to use
`update` so the image and the attachment are updated within the same
transaction. This is also what we do in most controllers.
[1] https://www.youtube.com/watch?v=tZ_WNUytO9o
