IssueTracker

Component used: Room
Version used: 1.0.0-alpha3

I've added one to many relationship in Room using Relation. I am able to fetch the entities while maintaining the relationship.
While storing the entities into the database resulted in `userId` to be empty which means there is no relation between the 2 tables.

1. User Entity (Kotlin):

@Entity
public class User {
    @PrimaryKey
    public int id; // User id
}

2. Pet Entity (Kotlin):

@Entity
public class Pet {
    @PrimaryKey
    public int id;     // Pet id
    public int userId; // User id
    public String name;
}

3. UserWithPets POJO (Java):

// Note: No annotation required at this class definition.
public class UserWithPets {
   @Embedded
   public User user;

   @Relation(parentColumn = "id", entityColumn = "userId", entity = Pet.class)
   public List<Pet> pets;
}
Now to fetch the records from DB we use the following DAO:

4. UserDao Dao (Kotlin):

@Dao
public interface UserDao {
    @Insert
    fun insertUser(user: User)

    @Query("SELECT * FROM User")
    public List<UserWithPets> loadUsersWithPets();
}

5. PetDao Dao (Kotlin):

@Dao
public interface PetDao {
    @Insert
    void insertAll(List<Pet> pets);
}

Current workaround:

Before inserting `User` and it's list of `Pets`. We need to manually iterate and set the value for `userId` in the `Pet`.
Something like this:

// Java
for(Pet pet : pets) {
    pet.setUserId(user.getId());
}
petDao.insertAll(pets);

StackOverFlow Link: https://stackoverflow.com/questions/44667160/android-room-insert-relation-entities-using-room