小编And*_*oro的帖子

我正在尝试使用新的Android Persistence Room Library在两个数据库表之间创建关系.我查看了文档,并尝试实现https://developer.android.com/reference/android/arch/persistence/room/Relation.html上的示例:

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

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

 }

 @Dao
 public interface UserDao {
     @Query("SELECT * from User")
     public List<User> loadUser();
 }

 @Dao
 public interface PetDao {
     @Query("SELECT * from Pet")
     public List<Pet> loadUserAndPets();
 }


 public class UserAllPets {
     @Embedded
     public User user;
     @Relation(parentColumn = "user.id", entityColumn = "userId", entity = Pet.class)
     public List pets;
 }

 @Dao
 public interface UserPetDao { …

基于我之前的问题(Android持久性空间:"无法弄清楚如何从光标读取此字段")我得到了工作,感谢反馈,我在Kolin中实现了相同的示例(请参阅下面的代码).我不得不做一些小改动,比如现在传递给查询的参数必须作为"p0","p1"等传递.现在在Kotlin中我得到以下与UserWithPets类相关的错误:

错误:无法弄清楚如何从游标中读取此字段.e:private java.util.List pets;

@Dao
interface UserDAO {   

    @get:Query("SELECT * FROM user")
    val all: LiveData<List<User>>

    @Insert
    fun insertUser(user: User) //single one

    @Insert(onConflict = OnConflictStrategy.REPLACE)
    fun insertUsers(vararg users: User)

    @Query("SELECT * FROM User")
    fun loadUsersWithPets(): LiveData<List<UserWithPets>>

}


@Entity
class Pet( var name: String?,  var ownerId: Int,@PrimaryKey(autoGenerate = true)var id:Int)



@Dao
interface PetDAO {
    @Query("SELECT * FROM pet")
    val all: List<Pet>

    @Query("SELECT * FROM pet WHERE id IN (:p0)")
    fun loadAllByIds(petIds: IntArray): List<Pet>


    @Insert
    fun insert(pet: Pet)

    @Insert
    fun insertAll(vararg …