View Source Arguments

To pass in data from the caller context and make it available in the rules, there's the args option. Any args passed to the Dx API function will be available in rules as if args was an association on the current root record.

Say we implement some authorization, where a user can archive a Todo.List only if they are an admin, or they are the owner of the list. We pass in the currently logged-in user struct, which was already loaded as part of authentication.

Dx.load!(list, args: [current_user: current_user])

The current_user is then available within args, including any fields, associations and predicates defined on it.

defmodule Todo.List do
  use Ecto.Schema
  use Dx.Ecto.Schema, repo: Todo.Repo

  schema "lists" do
    field :archived_at, :utc_datetime

    belongs_to :created_by, Todo.User

  infer can_archive?: true, when: %{args: %{current_user: %{is_admin?: true}}}
  infer can_archive?: true, when: %{created_by_id: {:ref, [:args, :current_user, :id]}}
  infer can_archive?: false