Data Layers

Data layers determine how resources are stored and retrieved. Examples of data layers:

• Postgres: For storing resources in PostgreSQL (via AshPostgres)
• ETS: For in-memory storage (Ash.DataLayer.Ets)
• Mnesia: For distributed storage (Ash.DataLayer.Mnesia)
• Embedded: For resources embedded in other resources (data_layer: :embedded) (typically JSON under the hood)
• Ash.DataLayer.Simple: For resources that aren't persisted at all. Leave off the data layer, as this is the default.

Specify a data layer when defining a resource:

defmodule MyApp.Post do
  use Ash.Resource,
    domain: MyApp.Blog,
    data_layer: AshPostgres.DataLayer

  postgres do
    table "posts"
    repo MyApp.Repo
  end

  # ... attributes, relationships, etc.
end

For embedded resources:

defmodule MyApp.Address do
  use Ash.Resource,
    data_layer: :embedded

  attributes do
    attribute :street, :string
    attribute :city, :string
    attribute :state, :string
    attribute :zip, :string
  end
end

Each data layer has its own configuration options and capabilities. Refer to the rules & documentation of the specific data layer package for more details.