Room Persistence @Relation在Java中起作用，但在Kolin中不起作用 [英] Room Persistence @Relation working in Java but not in Kolin

问题描述

基于我之前的问题()，由于反馈，我开始工作了，我在Kolin中实现了相同的示例(请参见下面的代码).我必须进行一些小的更改，例如现在传递给查询的参数，这些参数必须以"p0"，"p1"等形式传递. 现在在Kotlin中，我得到与UserWithPets类相关的以下错误:

Base on my previous question (Android Persistence room: "Cannot figure out how to read this field from a cursor") which I got to work thanks the feedback, I implemented the same example in Kolin (see code below). I had to make some minor changes like the parameters that are now passed to a the query which have to be passed as "p0", "p1" etc. Now in Kotlin I get the following error related to the UserWithPets class:

错误:无法弄清楚如何从光标读取此字段. e:私人java.util.List宠物；

error: Cannot figure out how to read this field from a cursor. 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 pets: Pet)

    @Delete
    fun delete(user: Pet)
}


class UserWithPets {
    @Embedded
    var user: User? = null

    @Relation(parentColumn = "id", entityColumn = "ownerId", entity = Pet::class)
    var pets: List<Pet>? = null
}

看来，如果我用Java编写UserWithPets类，它将很好地工作，但是用Kotlin编写时会失败.任何想法有什么问题吗?这是注释处理问题吗?

It appears that if I write the UserWithPets class in Java it will work fine, but fails when it is written in Kotlin. Any ideas what is wrong? Is this an annotation processing issue?

推荐答案

尝试更改查询@Query("SELECT * FROM pet WHERE id IN(:p0)")

try changing your query @Query("SELECT * FROM pet WHERE id IN (:p0)")

到 @Query("SELECT * FROM pet WHERE id IN (:petIds)")

kotlin和Room lib之间存在问题，Kotlin没有正确保留参数的实际参数名称，因此(:p0)/(:arg0)可以解决此问题，现在已解决.

There was an issue between kotlin and Room lib, Kotlin wasn't preserving the actual parameter names of the arguments properly, so (:p0)/(:arg0) was work around that, its resolved now.

我希望这能解决问题

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