【发布时间】：2022-08-10 20:42:42
【问题描述】：
我的应用程序中有一个SQLiteDataBase，包含三列。比我将它迁移到 Room 数据库如下：
@Database(entities = [Vehicle::class], version = 6, exportSchema = false)
abstract class VehicleDatabase : RoomDatabase() {
abstract val dao: Dao
companion object {
@Volatile
private var INSTANCE: VehicleDatabase? = null
private val migration = object : Migration(1, 5) {
override fun migrate(database: SupportSQLiteDatabase) {
database.apply {
execSQL(\"CREATE TABLE vehicles_tmp (_id INTEGER, Manufacturer TEXT, Model TEXT, Created TEXT, Modified TEXT, PRIMARY KEY(_id))\")
execSQL(\"INSERT INTO vehicles_tmp (_id, Manufacturer, Model, Created, Modified) SELECT _id, Manufacturer, Model, Date, Date FROM Vehicles\")
execSQL(\"DROP TABLE Vehicles\")
execSQL(\"ALTER TABLE vehicles_tmp RENAME TO Vehicles\")
execSQL(\"ALTER TABLE Vehicles ADD COLUMN Tags TEXT\")
}
}
}
private val addColor = object : Migration(5, 6) {
override fun migrate(database: SupportSQLiteDatabase) {
database.execSQL(\"ALTER TABLE Vehicles ADD COLUMN Color TEXT\")
}
}
fun getInstance(context: Context): VehicleDatabase = INSTANCE ?: synchronized(this) {
val instance = Room.databaseBuilder(
context.applicationContext,
VehicleDatabase::class.java,
\"Vehicles.db\"
)
.addMigrations(migration, addColor)
.build()
INSTANCE = instance
return instance
}
}
}
第一次迁移是从版本 1 到版本 5，如您所见，我又添加了一个列（颜色）。因此，我添加了从 5 到 6 的迁移。
一切正常，但现在我在 Firebase 中的 Crashlytics 出现了异常
Fatal Exception: android.database.sqlite.SQLiteException: duplicate column name: Color (code 1 SQLITE_ERROR): , while compiling: ALTER TABLE Vehicles ADD COLUMN Color TEXT
at android.database.sqlite.SQLiteConnection.nativePrepareStatement(SQLiteConnection.java)
at android.database.sqlite.SQLiteConnection.acquirePreparedStatement(SQLiteConnection.java:1055)
at android.database.sqlite.SQLiteConnection.prepare(SQLiteConnection.java:662)
at android.database.sqlite.SQLiteSession.prepare(SQLiteSession.java:590)
at android.database.sqlite.SQLiteProgram.<init>(SQLiteProgram.java:61)
at android.database.sqlite.SQLiteStatement.<init>(SQLiteStatement.java:33)
at android.database.sqlite.SQLiteDatabase.executeSql(SQLiteDatabase.java:1949)
at android.database.sqlite.SQLiteDatabase.execSQL(SQLiteDatabase.java:1871)
at androidx.sqlite.db.framework.FrameworkSQLiteDatabase.execSQL(FrameworkSQLiteDatabase.java:265)
at com.xxxxxxxx.xxxxxxxx.data.vehicles.NoteDatabase$Companion$addColor$1.migrate(VehicleDatabase.java:39)
at androidx.room.RoomOpenHelper.onUpgrade(RoomOpenHelper.java:99)
at androidx.sqlite.db.framework.FrameworkSQLiteOpenHelper$OpenHelper.onUpgrade(FrameworkSQLiteOpenHelper.java:183)
at android.database.sqlite.SQLiteOpenHelper.getDatabaseLocked(SQLiteOpenHelper.java:421)
at android.database.sqlite.SQLiteOpenHelper.getWritableDatabase(SQLiteOpenHelper.java:321)
at androidx.sqlite.db.framework.FrameworkSQLiteOpenHelper$OpenHelper.getWritableSupportDatabase(FrameworkSQLiteOpenHelper.java:151)
at androidx.sqlite.db.framework.FrameworkSQLiteOpenHelper.getWritableDatabase(FrameworkSQLiteOpenHelper.java:112)
at androidx.room.RoomDatabase.inTransaction(RoomDatabase.java:706)
at androidx.room.RoomDatabase.assertNotSuspendingTransaction(RoomDatabase.java:483)
at androidx.room.RoomDatabase.query(RoomDatabase.java:526)
at androidx.room.util.DBUtil.query(DBUtil.java:86)
at com.xxxxxxxx.xxxxxxxx.data.vehicles.Dao_Impl$9.call(Dao_Impl.java:262)
at com.xxxxxxxx.xxxxxxxx.data.vehicles.Dao_Impl$9.call(Dao_Impl.java:259)
at androidx.room.CoroutinesRoom$Companion$createFlow$1$1$1.invokeSuspend(CoroutinesRoom.java:128)
at kotlin.coroutines.jvm.internal.BaseContinuationImpl.resumeWith(BaseContinuationImpl.java:33)
at kotlinx.coroutines.DispatchedTask.run(DispatchedTask.java:106)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1167)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:641)
at java.lang.Thread.run(Thread.java:923)
为什么它会抛出那个异常？似乎它试图在已经添加的情况下添加该列。
还是我做错了什么？
-
猜测一下，您已更改 Vehicles Entity 类以合并新的颜色列，然后从全新安装（版本 5）运行，然后仅在运行后将版本号更改为 6。
标签： android android-room