Android房间迁移null错误

Posted 2023-03-14

【中文标题】Android房间迁移null错误

【英文标题】：Android room migration null error

【发布时间】：2018-05-13 17:10:09

【问题描述】：

当我在 android 上从旧的 sqlite 方式迁移到 Room 时，我需要使用“INTEGER NOT NULL”进行编译。 问题是，当迁移发生时，您正在使用“NOT NULL”参数在新表中插入 NULL 字段，我收到错误

android.database.sqlite.SQLiteConstraintException：NOT NULL 约束失败：note.notification_state（代码 1299）

编辑：

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:
                                                                            TableInfoname='note', columns=notification_date=Columnname='notification_date', type='TEXT', notNull=false, primaryKeyPosition=0, priority=Columnname='priority', type='INTEGER', notNull=true, primaryKeyPosition=0, description=Columnname='description', type='TEXT', notNull=false, primaryKeyPosition=0, title=Columnname='title', type='TEXT', notNull=false, primaryKeyPosition=0, id=Columnname='id', type='INTEGER', notNull=true, primaryKeyPosition=1, notification_state=Columnname='notification_state', type='INTEGER', notNull=true, primaryKeyPosition=0, created_date=Columnname='created_date', type='TEXT', notNull=false, primaryKeyPosition=0, foreignKeys=[], indices=[]
                                                                             Found:
                                                                            TableInfoname='note', columns=notification_date=Columnname='notification_date', type='TEXT', notNull=false, primaryKeyPosition=0, priority=Columnname='priority', type='INTEGER', notNull=false, primaryKeyPosition=0, title=Columnname='title', type='TEXT', notNull=false, primaryKeyPosition=0, description=Columnname='description', type='TEXT', notNull=false, primaryKeyPosition=0, id=Columnname='id', type='INTEGER', notNull=true, primaryKeyPosition=1, notification_state=Columnname='notification_state', type='INTEGER', notNull=false, primaryKeyPosition=0, created_date=Columnname='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(entities = 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");

    
;`

【问题讨论】：

如果您想要INTEGER NOT NULL，您将无法在该列中存储null 值。这不是特定于房间的。如果您现有的数据库允许该列的 null 值，请不要将其设为 NOT NULL 或弄清楚您要对现有的 null 值进行哪种转换。

问题是整数不能为空，否则编译时出错。

请编辑您的问题并发布minimal reproducible example，显示您的编译时错误和产生错误的代码。

【参考方案1】：

好的，我知道了，如果有人遇到同样的问题，请使用 NOT NULL DEFAULT 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");
            
        
    ;
    
    // ...

【参考方案2】：

迁移代码：

class Migration1To2: Migration(1, 2)
    override fun migrate(database: SupportSQLiteDatabase) 
        database.execSQL("ALTER TABLE 'table_name' ADD COLUMN 'row_to modify' INTEGER NOT NULL **DEFAULT 1"**)
    

---

 Dao Entity add **defaultValue = "1"**:
 @ColumnInfo( name="row_to modify", defaultValue = "1")
    var row_to modify: Int

【讨论】：

This 似乎是 Google Developers 文档。但是.. 你为什么选择 Kotlin？