迁移房间数据库，alter table, android?

Question

在我的应用程序中，我使用 ROOM 数据库来保存一些数据。

我有 table UserInfo 版本 1 中的一些列。

后来我在数据库中添加了一个整数列，我升级了数据库版本，添加了迁移代码但是我得到了下面的异常

Migration didn't properly handle UserInfo(ima.rvtech.model.api.result.UserInfo).
 Expected:
TableInfo{name='UserInfo', columns={
address=Column{name='address', type='TEXT', notNull=false, primaryKeyPosition=0}, 
password=Column{name='password', type='TEXT', notNull=false, primaryKeyPosition=0}, 
actBy=Column{name='actBy', type='TEXT', notNull=false, primaryKeyPosition=0}, 
emailId=Column{name='emailId', type='TEXT', notNull=false, primaryKeyPosition=0}, 
userType=Column{name='userType', type='TEXT', notNull=false, primaryKeyPosition=0}, 
pinCode=Column{name='pinCode', type='TEXT', notNull=false, primaryKeyPosition=0}, 
uploadImagePath=Column{name='uploadImagePath', type='TEXT', notNull=false, primaryKeyPosition=0}, 
loginId=Column{name='loginId', type='TEXT', notNull=false, primaryKeyPosition=0}, 
actDate=Column{name='actDate', type='TEXT', notNull=false, primaryKeyPosition=0}, 
contactNo=Column{name='contactNo', type='TEXT', notNull=false, primaryKeyPosition=0}, 
uploadVideoPath=Column{name='uploadVideoPath', type='TEXT', notNull=false, primaryKeyPosition=0}, 
edbNo=Column{name='edbNo', type='TEXT', notNull=false, primaryKeyPosition=0}, 
id=Column{name='id', type='INTEGER', notNull=true, primaryKeyPosition=1}, 
emergencyContactNo=Column{name='emergencyContactNo', type='TEXT', notNull=false, primaryKeyPosition=0}, 
bannerImagePath=Column{name='bannerImagePath', type='TEXT', notNull=false, primaryKeyPosition=0}, 
MyFriendListCount=Column{name='MyFriendListCount', type='INTEGER', notNull=true, primaryKeyPosition=0}, 
userName=Column{name='userName', type='TEXT', notNull=false, primaryKeyPosition=0}, 
operationType=Column{name='operationType', type='TEXT', notNull=false, primaryKeyPosition=0}}, foreignKeys=[], indices=[]}
 Found:
TableInfo{name='UserInfo', columns={
address=Column{name='address', type='TEXT', notNull=false, primaryKeyPosition=0},
 password=Column{name='password', type='TEXT', notNull=false, primaryKeyPosition=0}, 
actBy=Column{name='actBy', type='TEXT', notNull=false, primaryKeyPosition=0}, 
emailId=Column{name='emailId', type='TEXT', notNull=false, primaryKeyPosition=0}, 
userType=Column{name='userType', type='TEXT', notNull=false, primaryKeyPosition=0}, 
pinCode=Column{name='pinCode', type='TEXT', notNull=false, primaryKeyPosition=0},
 uploadImagePath=Column{name='uploadImagePath', type='TEXT', notNull=false, primaryKeyPosition=0}, 
loginId=Column{name='loginId', type='TEXT', notNull=false, primaryKeyPosition=0}, 
actDate=Column{name='actDate', type='TEXT', notNull=false, primaryKeyPosition=0}, 
contactNo=Column{name='contactNo', type='TEXT', notNull=false, primaryKeyPosition=0}, 
uploadVideoPath=Column{name='uploadVideoPath', type='TEXT', notNull=false, primaryKeyPosition=0}, 
edbNo=Column{name='edbNo', type='TEXT', notNull=false, primaryKeyPosition=0}, 
id=Column{name='id', type='INTEGER', notNull=true, primaryKeyPosition=1}, 
emergencyContactNo=Column{name='emergencyContactNo', type='TEXT', notNull=false, primaryKeyPosition=0}, 
bannerImagePath=Column{name='bannerImagePath', type='TEXT', notNull=false, primaryKeyPosition=0}, 
MyFriendListCount=Column{name='MyFriendListCount', type='INTEGER', notNull=false, primaryKeyPosition=0}, 
userName=Column{name='userName', type='TEXT', notNull=false, primaryKeyPosition=0}, 
operationType=Column{name='operationType', type='TEXT', notNull=false, primaryKeyPosition=0}}, foreignKeys=[], indices=[]}

我将在下一版本中添加一个整数列MyFriendListCount

下面是我的迁移代码

public static final Migration MIGRATION_1_2 = new Migration(1, 2) {
    @Override
    public void migrate(SupportSQLiteDatabase database) {
        database.execSQL("ALTER TABLE UserInfo "
                + " ADD COLUMN MyFriendListCount INTEGER");
    }
};

谁能告诉我这里缺少哪一段代码？

Answer 1

房间等待:-

MyFriendListCount=Column{name='MyFriendListCount', type='INTEGER', notNull=true, primaryKeyPosition=0},

您已提供：-

MyFriendListCount=Column{name='MyFriendListCount', type='INTEGER', notNull=false, primaryKeyPosition=0},

我相信你需要添加 NOT NULL 约束，所以也许使用 :-

public static final Migration MIGRATION_1_2 = new Migration(1, 2) {
    @Override
    public void migrate(SupportSQLiteDatabase database) {
        database.execSQL("ALTER TABLE UserInfo "
                + " ADD COLUMN MyFriendListCount INTEGER NOT NULL");
    }
};

Answer 2

从迈克的解决方案中得到帮助，帮助我理解，当您要使用 NOT NULL 时，您还需要将默认值设置为 column

public static final Migration MIGRATION_1_2 = new Migration(1, 2) {
    @Override
    public void migrate(SupportSQLiteDatabase database) {
        database.execSQL("ALTER TABLE UserInfo "
                + " ADD COLUMN MyFriendListCount INTEGER default 0 NOT NULL");

    }
};

Answer 3

For version from 2 to 3    

 val MIGRATION_2_3 = object : Migration(2, 3) {
        override fun migrate(database: SupportSQLiteDatabase) {
            //Integer values
            database.execSQL(
                "ALTER TABLE ProjectListingResponse "
                        + " ADD COLUMN dummy INTEGER default 0 NOT NULL"
            );
            //String values
            database.execSQL(
                "ALTER TABLE ProjectListingResponse "
                        + " ADD COLUMN dummy2 TEXT default 0 NOT NULL"
            );
        }
    }

  Room.databaseBuilder(context.applicationContext, AppDatabase::class.java,DATABASE_NAME)
                       // .fallbackToDestructiveMigration()         //will delete all existing data from device and update new schema
                       .addMigrations(MIGRATION_1_2, MIGRATION_2_3)  //Only update the schema much recomonded
                        .build()

迁移房间数据库，alter table, android?

Migration room database, alter table, android?

migration

sqlite

android

android-room