Anything from params can be user set. So you’re correct, don’t let the user set role to anything they typed into params.
In your specific example, I would create a function that uses the put_change function to set the role and transform the changeset using pipes.
changeset =
|> changeset(%User{}, params)
|> set_user_role("admin")
Repo.insert! changeset
...
def set_user_role(changeset, role) do
put_change(changeset, :role, role)
end
