如何檢查 Room 數據庫的完整性？

Question

我有以下簡單的數據庫：

NameList.kt

@Entity(tableName = "name_list")
data class NameList(
        @PrimaryKey(autoGenerate = true)
        var id: Long = 0L,

        @ColumnInfo(name = "name")
        var name: String = "")

NameListDao.kt

@Dao
interface NameListDao{    
    @Insert
    fun insert(nameList: NameList)

    @Update
    fun update(nameList: NameList)

    @Query("SELECT * FROM name_list ORDER BY id DESC")
    fun getAll(): LiveData<List<NameList>>
}

NameListRepository.kt

class NameListRepository(private val nameListDao: NameListDao){
    val allNames: LiveData<List<NameList>> = nameListDao.getAll()
}

現在，當我通過添加/刪除列來更改NameList.kt的表時，例如

@Entity(tableName = "name_list")
data class NameList(
        @PrimaryKey(autoGenerate = true)
        var id: Long = 0L,

        @ColumnInfo(name = "first_name")
        var firstName: String = "",

        @ColumnInfo(name = "last_name")
        var lastName: String = "")

在不刪除/更改手機上的數據庫的情況下，應用程序在訪問數據庫時崩潰並顯示以下錯誤消息：

E AndroidRuntime: java.lang.RuntimeException: Exception while computing database live data.
E AndroidRuntime:   at androidx.room.RoomTrackingLiveData$1.run(RoomTrackingLiveData.java:92)
E AndroidRuntime:   at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1167)
E AndroidRuntime:   at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:641)
E AndroidRuntime:   at java.lang.Thread.run(Thread.java:764)
E AndroidRuntime: Caused by: java.lang.IllegalStateException: Room cannot verify the data integrity. Looks like you've changed schema but forgot to update the version number. You can simply fix this by increasing the version number.
E AndroidRuntime:   at androidx.room.RoomOpenHelper.checkIdentity(RoomOpenHelper.java:154)
E AndroidRuntime:   at androidx.room.RoomOpenHelper.onOpen(RoomOpenHelper.java:135)
E AndroidRuntime:   at androidx.sqlite.db.framework.FrameworkSQLiteOpenHelper$OpenHelper.onOpen(FrameworkSQLiteOpenHelper.java:142)
E AndroidRuntime:   at android.database.sqlite.SQLiteOpenHelper.getDatabaseLocked(SQLiteOpenHelper.java:409)
E AndroidRuntime:   at android.database.sqlite.SQLiteOpenHelper.getWritableDatabase(SQLiteOpenHelper.java:298)
E AndroidRuntime:   at androidx.sqlite.db.framework.FrameworkSQLiteOpenHelper$OpenHelper.getWritableSupportDatabase(FrameworkSQLiteOpenHelper.java:92)
E AndroidRuntime:   at androidx.sqlite.db.framework.FrameworkSQLiteOpenHelper.getWritableDatabase(FrameworkSQLiteOpenHelper.java:53)
E AndroidRuntime:   at androidx.room.RoomDatabase.inTransaction(RoomDatabase.java:476)
E AndroidRuntime:   at androidx.room.RoomDatabase.assertNotSuspendingTransaction(RoomDatabase.java:281)
E AndroidRuntime:   at androidx.room.RoomDatabase.query(RoomDatabase.java:324)
E AndroidRuntime:   at androidx.room.util.DBUtil.query(DBUtil.java:83)

我知道這是由於表被更改（當我手動刪除數據庫並使用新實體創建新數據庫時，錯誤消失了）。

在訪問它之前，如何檢查數據庫/表的完整性（即它們的 NameList 數據庫是否與被訪問的數據庫匹配）？ Room 是否為此提供了一種我錯過的特定方法？

編輯：我想我現在知道版本錯誤是關於什么的。 但是，是否可以檢查完整性，以便在新舊數據庫不匹配的情況下，我可以做不同的事情，例如刪除舊數據庫或擁有兩個不同的數據庫等？

Answer 1

每次對結構進行一些更改時，都必須更新數據庫版本。 正如錯誤所說

您可以通過增加版本號來簡單地解決此問題。

Room 會照顧您以防止運行時崩潰。