ash/documentation/topics/identities.md

Identities

Identities can be used to describe the ways that a resource is uniquely identified. For example, you may have a user resource that has an id primary key, but is uniquely identifiable via the email attribute as well. To configure this, add an identities block inside of the resource block.

For example:

resource do
  identities do
    identity :unique_email, [:email]
  end
end

Effects

Identities are used in various ways across Ash and it's extensions. This list is not necessarily exhaustive:

Ash

• Identities can be used with c:Ash.Api.get/3, e.g MyApi.get(User, [email: "foo@bar.com"])

AshPostgres

• The migration generator creates unique constraints for identities

AshJsonApi

• Get routes can be configured to use a specific identity, creating a route like GET /users/foo@bar.com

AshGraphql

• Get queries and mutations can be configured to use a specific identity, to create a query like the following. (Arbitrary filtering is supported on list queries, this is is for creating queries that return a single result)

query{
  getUser(email: "foo@bar.com"){
      id
  }
}