get_or_create_category_by_name

something.ex

defmodule Something do
  def get_or_create_category_by_name(name) do
    Repo.transaction(fn ->
      case Repo.get_by(Category, name: name) do
        {:ok, category} ->
          category
        _ ->
          case create_category(%{name: name}) do
            {:ok, category} -> category
            {:error, error} -> Repo.rollback(error)
          end
      end
    end)
  end
end