android - 禁用 PRAGMA recursive_triggers

Question

android room documentation声明 PRAGMA recursive_triggers 默认启用:

By default, all RoomDatabases use in memory storage for TEMP tables and enables recursive triggers.

当我将插入与“onConflict(REPLACE)”一起使用时，这会给我带来问题:如果(且仅当)启用 recursice_triggers，这会触发我的 onDelete 触发器(请参阅 SQLite Documentation):

REPLACE [...] When the REPLACE conflict resolution strategy deletes rows in order to satisfy a constraint, delete triggers fire if and only if recursive triggers are enabled.[...]

我试图通过在 RoomDatabase.Callback.onCreate() 中添加 db.execSQL("PRAGMA recursive_triggers = 0;"); 来禁用它，但这没有任何效果。

    public static synchronized FnsDatabase getInstance(Context context){
        if (instance == null) {
            instance = Room.databaseBuilder(context, MyDb.class, "mydb.db")
                    .addCallback(triggerCallback)
                    .build();
        }
        return  instance;
    }

    private static RoomDatabase.Callback triggerCallback = new RoomDatabase.Callback(){
        @Override
        public void onCreate(@NonNull SupportSQLiteDatabase db) {
            super.onCreate(db);

            // adding some triggers here

            db.execSQL("PRAGMA recursive_triggers = 0;");

        }
    };

有人可以帮我解决这个问题吗？

Answer 1

改为在 RoomDatabase.Callback.onOpen() 中调用它。它需要在框架的 pragma 设置之后。您也不需要在方法覆盖中调用 super。