Just for clarity, is it not working in that you’re expecting to see an error returned in the changeset and not be able to submit the form? Or you’ve checked the actual database and seen that duplicate emails are being saved?
I’m not sure if I’m asking clearly, but I ask because unsafe_validate_unique/4 can be used to quickly return an invalid changeset error for UI purposes, and then you follow it up with a call to unique_constraint/3 to ensure the constraint at the database level.
Another thing to check, is that you are calling Ecto.Repo.insert/2 or Ecto.Repo.update/2 in your Users.create function from your Users.create(user_params) call.
