GreenDao版本更改
问题描述:
我在我的android项目中使用GreenDAO。我在GreenDAO中看到一个问题。每当我对现有表进行更改并更改版本以迁移更改时,GreenDAO都将删除所有表。 我试图对GreenDAO生成的文件进行更改,但它不会是正确的过程,但它不起作用。GreenDao版本更改
@Override
public void onUpgrade(Database db, int oldVersion, int newVersion) {
Log.i("greenDAO", "Upgrading schema from version " + oldVersion + " to " + newVersion + " by dropping all tables");
dropAllTables(db, true);
onCreate(db);
}
我试着在上面的代码没有奏效评论dropAllTables
,代码再生上运行的代码?有谁知道如何解决它?
编辑:
我看到与此相关的问题,几个问题,但他们都老了线程并没有帮助我。
答
您可以扩展DaoMaster.DevOpenHelper
并提供您自己的实现onUpgrade
。
实现自己DevOpenHelper
public class MyOpenHelper extends DaoMaster.DevOpenHelper {
//..
//override the constructor here by calling super
//..
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
switch(oldVersion) {
case 1:
//upgrade logic from version 1 to 2
/* break was omitted by purpose. */
case 2:
//upgrade logic from version 2 to 3
/* break was omitted by purpose. */
case 3:
//upgrade logic from version 3 to 4
break;
default:
throw new IllegalStateException(
"unknown oldVersion " + oldVersion);
}
}
}
实例化类
DaoMaster.DevOpenHelper helper = new MyOpenHelper(this, databaseName, null);
SQLiteDatabase db = helper.getWritableDatabase();
DaoMaster daoMaster = new DaoMaster(db);
有关详细信息,我结账是如何做的here。