预打包数据库的架构列顺序无效

如何解决预打包数据库的架构列顺序无效

我正在尝试在我的 Android 应用程序中实现 Room，但出现错误

java.lang.IllegalStateException: Pre-packaged database has an invalid schema: viewLog(myApp.ViewLogModel).
 
Expected:
TableInfo{name='viewLog',columns={vid=Column{name='vid',type='INTEGER',affinity='3',notNull=true,primaryKeyPosition=0,defaultValue='null'},mid=Column{name='mid',primaryKeyPosition=1,uts=Column{name='uts',type='REAL',affinity='4',defaultValue='null'}},foreignKeys=[],indices=[]}
 
Found:
TableInfo{name='viewLog',columns={VID=Column{name='VID',UTS=Column{name='UTS',MID=Column{name='MID',indices=[]}

我确实看到 uts 和 mid 列被切换，但是我一直无法弄清楚如何更改 TableInfo 中的列顺序。

我的房间数据库代码是

@Database(entities = [ViewLogModel::class,CacheInputModel::class,CachePageModel::class],version = 1)
    abstract class MyDatabase : RoomDatabase() {
    abstract fun cacheInputDao(): CacheInputDao
    abstract fun cachePageDao(): CachePageDao
    abstract fun viewLogDao(): ViewLogDao

    companion object {
        // For Singleton Instance
        @Volatile
        private var INSTANCE: MyDatabase? = null

        fun getAppDataBase(context: Context): MyDatabase {
            return INSTANCE ?: synchronized(this) {
                INSTANCE ?: Room.databaseBuilder(context.applicationContext,MyDatabase::class.java,"appDatabase")
                    .createFromAsset("app.db")
                    .build()
            }
        }

        fun destroyDataBase(){
            INSTANCE = null
        }
    }
}

ViewLogModel 是

@Entity(tableName = "viewLog")
data class ViewLogModel(
    @PrimaryKey val mid: Int,val vid: Int,val uts: Float)

ViewLogDao 是

@Dao
interface ViewLogDao {
    @Insert(onConflict = OnConflictStrategy.REPLACE)
    suspend fun insertOrUpdateViewLog(viewLog: ViewLogModel)

    @Update
    suspend fun updateViewLog(viewLog: ViewLogModel)

    @Delete
    suspend fun deleteallViewLog(viewLog: ViewLogModel)

    @Query("DELETE FROM viewlog WHERE VID= :vid OR UTS < :uts")
    suspend fun deleteViewLog(vid: Int,uts: Float)

    @Query("SELECT * FROM viewLog")
    suspend fun getAll(): List<ViewLogModel>

    @Query("SELECT * FROM viewLog WHERE vid = :vid")
    suspend fun getViewLog(vid: Int): List<ViewLogModel>
}

如果这是我遇到的问题，有人可以帮我订购列吗？

解决方法

我认为您的问题不在于顺序，而在于列名的大小写。

例如以下数据库（另存为资产 appcase.db）定义为：-

CREATE TABLE "viewLog" (
  "MID" INTEGER NOT NULL,"UTS" real NOT NULL,"VID" INTEGER NOT NULL,PRIMARY KEY ("MID")
);

失败：-

 Caused by: java.lang.IllegalStateException: Pre-packaged database has an invalid schema: viewLog(a.a.so67711264kotlinroomprepackageddb.ViewLogModel).
 Expected:
TableInfo{name='viewLog',columns={vid=Column{name='vid',type='INTEGER',affinity='3',notNull=true,primaryKeyPosition=0,defaultValue='null'},mid=Column{name='mid',primaryKeyPosition=1,uts=Column{name='uts',type='REAL',affinity='4',defaultValue='null'}},foreignKeys=[],indices=[]}
 Found:
TableInfo{name='viewLog',columns={VID=Column{name='VID',UTS=Column{name='UTS',type='real',MID=Column{name='MID',indices=[]}

但是，使用 DDL 的数据库是：-

CREATE TABLE "viewLog" (
  "mid" INTEGER NOT NULL,"uts" real NOT NULL,"vid" INTEGER NOT NULL,PRIMARY KEY ("mid")
)

按预期工作。

因此，您需要像上面一样更改 DDL 或更改实体以反映 DDL，例如以下适用于原始（失败的）DDL：-

@Entity(tableName = "viewLog")
data class ViewLogModel(
    @PrimaryKey val MID: Int,val VID: Int,val UTS: Float)

或者您也可以使用 @ColumnInfo 之类的：-

@Entity(tableName = "viewLog")
data class ViewLogModel(
    @PrimaryKey @ColumnInfo(name = "MID") val mid: Int,@ColumnInfo(name ="VID") val vid: Int,@ColumnInfo(name = "UTS") val uts: Float)