ArangoXEcto.Schema.one_outgoing

You're seeing just the macro one_outgoing, go back to ArangoXEcto.Schema module for more information.
Link to this macro

one_outgoing(name, target, opts \\ [])

View Source (macro)

Defines an outgoing relationship of one object

Unlike outgoing/3, this does not create a graph relation and instead places the _id in a field in the incoming schema. This MUST be accompanied by a one_incoming/3 definition in the other target schema.

Behind the scenes this injects the __id__ field to store the _id value and uses the built-in Ecto has_one/3 function.

Options passed to the opts attribute are passed to the has_many/3 definition. Refrain from overriding the :references and :foreign_key attributes unless you know what you are doing.

Example

defmodule MyProject.User do
  use ArangoXEcto.Schema

  schema "users" do
    field :name, :string

    one_outgoing :best_post, MyProject.Post
  end
end