QObject 在放入 QML 变量后被销毁 [英] QObject gets destroyed after being put into QML variable

问题描述

今天我在我们的程序中遇到了奇怪的错误.从 QObject 继承的类的对象正在被类型为 QEvent::DefferedDelete 的事件删除，而没有人可能发送它.

Today I've faced strange bug in our program. The object of a class inherited from QObject was being deleted by event with type QEvent::DefferedDelete, while nobody could possibly send it.

它作为 QVariant 传入 QML:

It was passed into QML as QVariant:

// cpp: 
        Q_INVOKABLE QVariant currentDevice_v() const {
            return QVariant::fromValue(_current);
        }
// qml: 
       Component.onCompleted: {
            curDevice = devicesModel.currentDevice_v()
            #...
       }

没有那条 qml 行，一切都运行良好 - 不会产生删除事件.

Without that qml line everything worked well - nothing produces delete event.

推荐答案

我发现如果我在将 QObject 传递给 QML 之前设置它的父级，那么它不会't 被删除.因此，我得出的结论是，将非父级 QObject 传递到 QML 范围会使该范围成为 QObject 的父级，并在范围结束后调用其析构函数.

What I've figured out that if I set the parent of that QObject before I pass it into QML, then it doesn't get deleted. So, I've concluded that passing unparented QObject into QML scope makes that scope become a parent of QObject and call its destructor after scope ends.

分享这个，因为我在任何地方都没有找到答案.但是在写这篇文章时，我发现了类似的未解决的问题:Qt5.6 QML，为什么垃圾回收后动态模型会被销毁?

Sharing this out, as I haven't found an answer anywhere. But while writing this post I've found similar unanswered issue: Qt5.6 QML, why are dynamic models destroyed after garbage collection?

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