has_many through not rolling back when validation fails

[austinbachman]

When a model has_many through, and an association is added when editing the record, but a validation fails when the record is saved, the join table record remains. It appears that the association is being created in a separate transaction than the save, and so it is not being rolled back when the save fails. Although I believe this should not be the expected behavior, please advise if there are any workarounds for this to remove the join record, as when removing them explicitly when validation fails, that change is rolled back and they still persist.

[darrenterhune]

Due to this line https://github.com/sferik/rails_admin/blob/master/lib/rails_admin/config/actions/edit.rb#L27 which calls assign_attributes in rails which doesn't use validators and is separate from the save so rollbacks don't rollback the associations collection assignments. Also experienced this problem and our solution is building our own admin ui.