我尝试通过添加新字段来更新我的房间实体：
版本1：
@Entity(tableName = TABLE_NAME)
data class AvailableAccountRoom(
@PrimaryKey
val id: String = "",
[...]
)版本2：
@Entity(tableName = TABLE_NAME)
data class AvailableAccountRoom(
@PrimaryKey
val id: String = "",
[...]
val isExchangeSupported: Boolean,
)我想使用自动迁移，所以我也添加这一行到我的数据库：
autoMigrations = [
AutoMigration(from = 1, to = 2)
]但我有运行时崩溃与下一条消息：
(1) no such column: isExchangeSupported in "INSERT INTO `_new_table_name` (`id`,`isExchangeSupported`
(1) no such column: isExchangeSupported in "INSERT INTO `_new_table_name` (`id`,`isExchangeSupported`
FATAL EXCEPTION: OkHttp Dispatcher
Process: ...
android.database.sqlite.SQLiteException: no such column: isExchangeSupported (code 1 SQLITE_ERROR): , while compiling: INSERT INTO
`_new_table_name` (`id`,`isExchangeSupported`) SELECT
`id`,`isExchangeSupported` FROM
`table_name `
at android.database.sqlite.SQLiteConnection.nativePrepareStatement(Native Method)
at android.database.sqlite.SQLiteConnection.acquirePreparedStatement(SQLiteConnection.java:1068)
at android.database.sqlite.SQLiteConnection.prepare(SQLiteConnection.java:673)
at android.database.sqlite.SQLiteSession.prepare(SQLiteSession.java:590)
at android.database.sqlite.SQLiteProgram.<init>(SQLiteProgram.java:62)
at android.database.sqlite.SQLiteStatement.<init>(SQLiteStatement.java:34)
at android.database.sqlite.SQLiteDatabase.executeSql(SQLiteDatabase.java:2086)
at android.database.sqlite.SQLiteDatabase.execSQL(SQLiteDatabase.java:2008)
at androidx.sqlite.db.framework.FrameworkSQLiteDatabase.execSQL(FrameworkSQLiteDatabase.kt:246)
at com.###.AppDatabase_AutoMigration_1_2_Impl.migrate(AppDatabase_AutoMigration_1_2_Impl.java:18)
at androidx.room.RoomOpenHelper.onUpgrade(RoomOpenHelper.kt:91)
at androidx.sqlite.db.framework.FrameworkSQLiteOpenHelper$OpenHelper.onUpgrade(FrameworkSQLiteOpenHelper.kt:253)
at android.database.sqlite.SQLiteOpenHelper.getDatabaseLocked(SQLiteOpenHelper.java:416)
at android.database.sqlite.SQLiteOpenHelper.getWritableDatabase(SQLiteOpenHelper.java:316)
at androidx.sqlite.db.framework.FrameworkSQLiteOpenHelper$OpenHelper.getWritableOrReadableDatabase(FrameworkSQLiteOpenHelper.kt:232)
at androidx.sqlite.db.framework.FrameworkSQLiteOpenHelper$OpenHelper.innerGetDatabase(FrameworkSQLiteOpenHelper.kt:190)
at androidx.sqlite.db.framework.FrameworkSQLiteOpenHelper$OpenHelper.getSupportDatabase(FrameworkSQLiteOpenHelper.kt:151)
at androidx.sqlite.db.framework.FrameworkSQLiteOpenHelper.getWritableDatabase(FrameworkSQLiteOpenHelper.kt:104)
at androidx.room.RoomDatabase.inTransaction(RoomDatabase.kt:638)
at androidx.room.RoomDatabase.assertNotSuspendingTransaction(RoomDatabase.kt:457)
at androidx.room.RoomDatabase.query(RoomDatabase.kt:486)
at androidx.room.util.DBUtil.query(DBUtil.kt:75)
at com.###Dao_Impl$6.call(LoginTokenDao_Impl.java:156)
at com.###Dao_Impl$6.call(LoginTokenDao_Impl.java:153)
at androidx.room.CoroutinesRoom$Companion$execute$4$job$1.invokeSuspend(CoroutinesRoom.kt:88)
at kotlin.coroutines.jvm.internal.BaseContinuationImpl.resumeWith(ContinuationImpl.kt:33)我还尝试在实体中指定新字段的默认值：
val isExchangeSupported: Boolean = false,但我也有同样的错误
我做错了什么？一般来说，我只需要迁移一个不改变的表，其余的可以删除，但我没有找到这样做的方法，所以我使用自动迁移。但这不起作用。任何解决办法都对我有好处，先谢谢你了
2条答案
按热度按时间mw3dktmi1#
对于任何可能遇到同样问题的人，
观察结果：如果您在递增数据库版本之前构建应用程序，则可能会发生这种情况，当room尝试执行迁移时，源JSON模式将被解释为与目标JSON模式相同
解决方案：修改源JSON模式以匹配旧版本，然后重新构建，或者如果您将其置于版本控制之下，则只需重置为提交的版本
注意：JSON schema是指定义你的数据库schema的房间自动生成的JSON文件
yqkkidmi2#
@Remc4评论：* 同时检查您的版本1模式文件。如果它包含isExchangeSupported字段，则您可能在增加版本号之前运行了生成项目。*
他说的完全正确，这个项目是在我添加迁移之前构建的，所以它已经在1模式中包含了这个字段。
所以要解决这个问题