android - 房间错误 : Type of the parameter must be a class annotated with @Entity or a collection/array of it

Question

我收到以下错误:

error: Type of the parameter must be a class annotated with @Entity or a collection/array of it.
    java.lang.String matchId);

在我的 matchedBefore() 查询中:

@Dao
interface MatchedUsersDao {

    // Checks to see if user has matched before (if it returns 1)
    @Query("SELECT COUNT(*) FROM matched_users WHERE :matchId = match_id LIMIT 1")
    fun matchedBefore(matchId: String): Int

    @Insert(onConflict = OnConflictStrategy.ABORT)
    fun addMatchUid(matchId: String)
}

这是我的实体

@Entity(tableName = "matched_users")
data class MatchedUser(
    @PrimaryKey(autoGenerate = true) val id: Int,
    @ColumnInfo(name = "match_id") val matchId: String
)

数据库

@Database(entities = arrayOf(MatchedUser::class), version = 1)
abstract class AppDatabase : RoomDatabase() {

    abstract fun matchedUsersDao(): MatchedUsersDao
}

然后我在我的应用程序中实例化我的数据库:

class CustomApplication : Application() {

    companion object {
        var database: AppDatabase? = null
    }

    override fun onCreate() {
        super.onCreate()
        CustomApplication.database = Room.databaseBuilder(this, AppDatabase::class.java, "AppDatabase").build()
    }

谁能告诉我错误是什么意思以及我该如何解决？

Answer 1

你的问题是这一行

@Insert(onConflict = OnConflictStrategy.ABORT)
fun addMatchUid(matchId: String)

如果您想使用 @Insert 注释，您必须发送 MatchedUser 的实例，而不是 String。

所以你可以:

1) 使用您的 ID 发送新的 MatchedUser(使用您的 ID 插入空的 MatchedUser)

你的代码必须是这样的

@Insert(onConflict = OnConflictStrategy.ABORT)
fun addMatchUid(matchUser: MatchedUser)

2) 编写了新的 @Query 用于在数据库中插入 id