Room：java.lang.IllegalStateException：现有数据库的迁移不正确

Question

我有一个由Ormlite实现的现有数据库。我正在尝试用Ormlite生成的现有sqlite文件迁移到Room。

当我们在ormlite中为表列使用long数据类型时，它在SQLite中被转换为BIGINT。因此，创建的模式包含BIGINT类型的列，而BIGINT类型对于Room是未知的。当我尝试用Room升级应用程序时，我遇到了迁移异常。

java.lang.IllegalStateException：迁移不正确

Process: com.sample.playground, PID: 5587
java.lang.IllegalStateException: Migration didn't properly handle SampleReports(com.sample.playground.model.SampleReport
 Expected:
TableInfo{name='SampleReports', columns={timeslot=Column{name='timeslot', type='INTEGER', affinity='3', notNull=true, primaryKeyPosition=0}, environment=Column{name='environment', type='TEXT', affinity='2', notNull=true, primaryKeyPosition=0}, timestamp=Column{name='timestamp', type='INTEGER', affinity='3', notNull=true, primaryKeyPosition=0}, trigger=Column{name='trigger', type='INTEGER', affinity='3', notNull=true, primaryKeyPosition=0}, imeisvSvn=Column{name='imeisvSvn', type='TEXT', affinity='2', notNull=false, primaryKeyPosition=0}, _id=Column{name='_id', type='INTEGER', affinity='3', notNull=true, primaryKeyPosition=1}}, foreignKeys=[], indices=[]}
 Found:
TableInfo{name='SampleReports', columns={environment=Column{name='environment', type='TEXT', affinity='2', notNull=true, primaryKeyPosition=0}, timeslot=Column{name='timeslot', type='BIGINT', affinity='3', notNull=true, primaryKeyPosition=0}, trigger=Column{name='trigger', type='INTEGER', affinity='3', notNull=true, primaryKeyPosition=0}, timestamp=Column{name='timestamp', type='BIGINT', affinity='3', notNull=true, primaryKeyPosition=0}, _id=Column{name='_id', type='INTEGER', affinity='3', notNull=false, primaryKeyPosition=1}}, foreignKeys=[], indices=[]}
    at com.sample.playground.model.SampleReport.SampleReportRoomDbHelper_Impl$1.validateMigration(SampleReportRoomDbHelper_Impl.java:77)
    at android.arch.persistence.room.RoomOpenHelper.onUpgrade(RoomOpenHelper.java:87)
    at android.arch.persistence.db.framework.FrameworkSQLiteOpenHelper$OpenHelper.onUpgrade(FrameworkSQLiteOpenHelper.java:133)
    at android.database.sqlite.SQLiteOpenHelper.getDatabaseLocked(SQLiteOpenHelper.java:256)
    at android.database.sqlite.SQLiteOpenHelper.getWritableDatabase(SQLiteOpenHelper.java:163)
    at android.arch.persistence.db.framework.FrameworkSQLiteOpenHelper$OpenHelper.getWritableSupportDatabase(FrameworkSQLiteOpenHelper.java:96)
    at android.arch.persistence.db.framework.FrameworkSQLiteOpenHelper.getWritableDatabase(FrameworkSQLiteOpenHelper.java:54)
    at android.arch.persistence.room.RoomDatabase.query(RoomDatabase.java:233)
    at com.sample.playground.model.SampleReportDao_Impl.getReports(SampleReportDao_Impl.java:300)

Answer 1

我认为您需要相应地转换表，方法是重写migrate方法，以便它-创建一个基于预期列的中间表，-将数据复制到中间表，-删除原始表，然后将中间表的名称更改为原始名称

例如基于：-

DROP TABLE IF EXISTS SampleReports_intermediate;
CREATE TABLE IF NOT EXISTS SampleReports_intermediate (
    timeslot INTEGER NOT NULL, 
    environment TEXT NOT NULL,
    timestamp INTEGER NOT NULL,
    `trigger` INTEGER NOT NULL,
    imeisvSvn TEXT,
    _id INTEGER PRIMARY KEY
);
INSERT INTO SampleReports_intermediate (environment, timeslot, `trigger`, timestamp, _id)
    SELECT environment, timeslot,`trigger`, timestamp, _id FROM SampleReports
;
DROP TABLE IF EXISTS SampleReports;
ALTER TABLE SampleReports_intermediate RENAME TO SampleReports;

如果你不是在使用1.1号房间，试着用它，因为它有：-