Embedded entities are used to design value objects in your Java domain model whose properties are flattened out into the table.
In the following example you see, that User.name is annotated with Embedded.
The consequence of this is that all properties of `UserName` are folded into the `user` table which consists of 3 columns (user_id, firstname, lastname).
Embedded entities may only contain simple property types. It is not possible to nest an embedded entity into another embedded one.
However, if the firstname and lastname column values are actually null within the result set, the entire property name will be set to null according to the onEmpty of Embedded, which nulls objects when all nested properties are null.
Opposite to this behaviour USE_EMPTY tries to create a new instance using either a default constructor or one that accepts nullable parameter values from the result set.
public class User {
@PrimaryKey("user_id")
private String userId;
@Embedded(onEmpty = USE_NULL)
UserName name;
}
public class UserName {
private String firstname;
private String lastname;
}
Original pull request: #173.
a59d012fb9