Create a row associated to another table with a unique value and not the foreign_key assigned

Questions / Help
,
1

Hello everyone.
I’ve been wondering if i’m taking the wrong approach.
I want to be able to create a new comment associated to an author by its unique author_name, but the foreign key assigned to comments is author_id. I want both of these unique values to work author_id and author_name, since they do not repeat.

My migrations are:

defmodule MyApp.Repo.Migrations.CreateAuthors do
  use Ecto.Migration

  def up do
    create table(:authors) do
      add(:last_name, :string)
      add(:name, :string)

        timestamps()
    end

    create unique_index(:authors, [:name])
  end
end

defmodule MyApp.Repo.Migrations.CreateComments do
  use Ecto.Migration

  def up do
    create table(:comments) do
      add(:author_id, references(:authors, on_delete: :nothing))
      add(:body, :string)

      timestamps()
    end

    create(index(:comments, [:author_id]))
  end
end

The create mutation I want to make with author_name instead of author_id:

mutation{
  createComment(body: "Hello world!" author_name: "Anna"){
    id
    body
  }
}

I’m looking for a double foreign key of some kind. Is there an easy approach in Ecto to this?