RelationalDatumEntity class abstract

An extension of DatumEntity that includes support for defining relationships.

Understanding Relationships

The key difference between BelongsTo, HasOne, and HasMany lies in which entity holds the foreign key.

BelongsTo

Use this when the current entity's table contains the foreign key that points to the parent.

// In a Post entity:
class Post extends RelationalDatumEntity {
  final String userId; // Foreign key
  @override
  Map<String, Relation> get relations => {'author': BelongsTo<User>(this, 'userId')};
}

HasOne / HasMany

Use these when the other entity's table contains the foreign key that points back to this one.

// In a User entity:
class User extends RelationalDatumEntity {
  @override
  Map<String, Relation> get relations => {
    'profile': HasOne<Profile>(this, 'userId'), // A Profile has a `userId` field
    'posts': HasMany<Post>(this, 'userId'),   // A Post has a `userId` field
  };
}

Entities that have relationships with other syncable entities should extend this class instead of DatumEntity directly.