Android room迁移空错误

Question

当我在Android上从旧的sqlite方式迁移到Room时，我需要使用“integer NOT null”来编译。问题是，当迁移发生时，您在新表中插入了带有“not NULL”参数的NULL字段，而我得到了错误

Android.database.sqlite.sqliteConstraintException：NOT NULL约束失败：note.notification_state（代码1299）

11-29 22:52:58.891 14605-14630/com.aleksandarvasilevski.notes E/AndroidRuntime: FATAL EXCEPTION: pool-1-thread-1
                                                                            Process: com.aleksandarvasilevski.notes, PID: 14605
                                                                            java.lang.IllegalStateException: Migration didn't properly handle note(com.aleksandarvasilevski.notes.repository.db.Note).
                                                                             Expected:
                                                                            TableInfo{name='note', columns={notification_date=Column{name='notification_date', type='TEXT', notNull=false, primaryKeyPosition=0}, priority=Column{name='priority', type='INTEGER', notNull=true, primaryKeyPosition=0}, description=Column{name='description', type='TEXT', notNull=false, primaryKeyPosition=0}, title=Column{name='title', type='TEXT', notNull=false, primaryKeyPosition=0}, id=Column{name='id', type='INTEGER', notNull=true, primaryKeyPosition=1}, notification_state=Column{name='notification_state', type='INTEGER', notNull=true, primaryKeyPosition=0}, created_date=Column{name='created_date', type='TEXT', notNull=false, primaryKeyPosition=0}}, foreignKeys=[], indices=[]}
                                                                             Found:
                                                                            TableInfo{name='note', columns={notification_date=Column{name='notification_date', type='TEXT', notNull=false, primaryKeyPosition=0}, priority=Column{name='priority', type='INTEGER', notNull=false, primaryKeyPosition=0}, title=Column{name='title', type='TEXT', notNull=false, primaryKeyPosition=0}, description=Column{name='description', type='TEXT', notNull=false, primaryKeyPosition=0}, id=Column{name='id', type='INTEGER', notNull=true, primaryKeyPosition=1}, notification_state=Column{name='notification_state', type='INTEGER', notNull=false, primaryKeyPosition=0}, created_date=Column{name='created_date', type='TEXT', notNull=false, primaryKeyPosition=0}}, foreignKeys=[], indices=[]}
                                                                                at com.aleksandarvasilevski.notes.repository.db.NoteDatabase_Impl$1.validateMigration(NoteDatabase_Impl.java:70)
                                                                                at android.arch.persistence.room.RoomOpenHelper.onUpgrade(RoomOpenHelper.java:75)
                                                                                at android.arch.persistence.db.framework.FrameworkSQLiteOpenHelper$OpenHelper.onUpgrade(FrameworkSQLiteOpenHelper.java:118)
                                                                                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:93)
                                                                                at android.arch.persistence.db.framework.FrameworkSQLiteOpenHelper.getWritableDatabase(FrameworkSQLiteOpenHelper.java:54)
                                                                                at android.arch.persistence.room.RoomDatabase.query(RoomDatabase.java:193)
                                                                                at com.aleksandarvasilevski.notes.repository.db.NoteDao_Impl$5.compute(NoteDao_Impl.java:195)
                                                                                at com.aleksandarvasilevski.notes.repository.db.NoteDao_Impl$5.compute(NoteDao_Impl.java:181)
                                                                                at android.arch.lifecycle.ComputableLiveData$2.run(ComputableLiveData.java:87)
                                                                                at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1133)
                                                                                at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:607)
                                                                                at java.lang.Thread.run(Thread.java:761)

代码：

`@database（实体={note.class}，版本=3）公共抽象类NoteDatabase扩展RoomDatabase{

public static final Migration MIGRATION_2_3 = new Migration(2, 3) {
    @Override
    public void migrate(@NonNull SupportSQLiteDatabase database) {

        database.execSQL(
                "CREATE TABLE note (id INTEGER NOT NULL, title TEXT, description TEXT, created_date TEXT, notification_date TEXT, notification_state INTEGER, priority INTEGER, PRIMARY KEY(id))");


        database.execSQL(
                "INSERT INTO note (id, title, description, created_date) SELECT _ID, title, description, date FROM notes");

    }
};`

Answer 1

好的，我让它工作，如果任何人有相同的问题，只需使用NOT NULL默认值0（或其他数字）。

@Database(entities = {Note.class}, version = 3)
public abstract class NoteDatabase extends RoomDatabase {

    public static final Migration MIGRATION_2_3 = new Migration(2, 3) {
        @Override
        public void migrate(@NonNull SupportSQLiteDatabase database) {

            database.execSQL(
                    "CREATE TABLE note (id INTEGER NOT NULL, " +
                    "title TEXT, description TEXT, created_date TEXT, notification_date TEXT, " +
                    "notification_state INTEGER NOT NULL DEFAULT 0, " +
                    "priority INTEGER NOT NULL DEFAULT 0, PRIMARY KEY(id))");
            
            database.execSQL(
                    "INSERT INTO note (id, title, description, created_date) " +
                    "SELECT _ID, title, description, date FROM notes");
            
        }
    };
    
    // ...

}