if pet.GetOwner() != nil {
		petOwner := int(pet.GetOwner().GetId())
		m.SetOwnerID(petOwner)  // <- SetOwnerID undefined since the edge is immutable.
	}

// Edges of the Person.
func (Person) Edges() []ent.Edge {
	return []ent.Edge{
		edge.To("pets", Pet.Type).
			Annotations(entproto.Field(2)),
	}
}

// Edges of the Pet.
func (Pet) Edges() []ent.Edge {
	return []ent.Edge{
		edge.From("owner", Person.Type).Ref("pets").Immutable().Unique().Required().
		Annotations(entproto.Field(2)),
	}
}