Hi everyone, I’m running into this error I absolutely can’t make sense of while working with Ecto.Multi (I’m relatively new but feel like I have a decent grasp) and so far Google searches haven’t yielded anything.

Here is the error:

expected Ecto.Multi callback named `:relationship` to return either {:ok, value} or {:error, value}, got: {:error, :relationship, "not found", %{}}

Now I am testing a failure case, but I am expecting an error to get passed through so that the view can display an error instead of an exception. The weird thing is I have inspected the value returned from the anonymous function in Multi.run and the value is {:error, :not_found} which based on this error message I think should be fine?

Here is the function that is running into this error:

def update_relationship(%SocialUser{} = user_a, %SocialUser{} = user_b, %{} = info_attrs, with_changeset) do
    Multi.new()
    |> Multi.run(:relationship, fn _repo, _changes -> get_relationship(user_a, user_b) end)
    |> Multi.update(:update, fn %{relationship: %{info: info}} -> with_changeset.(info, info_attrs) end)
    |> Repo.transaction()
  end

Here is the code for get_relationship/2:

  def get_relationship(%SocialUser{} = user_a, %SocialUser{} = user_b) do
    Repo.get_one(from r in Relationship, where: r.user_a_id == ^user_a.id and r.user_b_id == ^user_b.id, preload: [:info])
  end

And finally Repo.get_one is a function I’ve written to make it easier to work with Repo.one in situations like this where you need a tuple:

  def get_one(query) do
     case one(query) do
       nil -> { :error, :not_found }
       row -> { :ok, row }
     end
  end

Am I doing something stupid? I can’t for the life of me figure out where this transformation of {:error, :not_found} to {:error, :relationship, "not found", %{}} is happening, as far as I can tell I’m following what the documentation says