C++ 如何将 QVariant 转换为自定义类？
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How can I cast a QVariant to custom class?
提问by J.M.J
I'm developing a BlackBerry 10 mobile application using the Momentics IDE (native SDK).
我正在使用 Momentics IDE（本机 SDK）开发 BlackBerry 10 移动应用程序。
I have a listview which I want to handle its items click with C++ (I need to use C++ not QML).
我有一个列表视图，我想用 C++ 处理它的项目点击（我需要使用 C++ 而不是 QML）。
I can get the index path using the "connect" instruction, but I have problem with parsing a QVariant to a custom class ;
我可以使用“connect”指令获取索引路径，但是我在将 QVariant 解析为自定义类时遇到问题；
Q_ASSERT(QObject::connect(list1, SIGNAL(triggered(QVariantList)), this, SLOT(openSheet(QVariantList))));
QVariant selectItem = m_categoriesListDataModel->data(indexPath);
I tried to use the static cast like below
我尝试使用如下所示的静态转换
Category* custType = static_cast<Category*>(selectItem);
but it returns :
但它返回：
"invalid static_cast from type 'QVariant' to type 'Category*'"
Can anyone help me on this ?
谁可以帮我这个事 ？
回答by epsilon
EDIT: works for non QObject derived type (see Final Contest's answer for this case)
编辑：适用于非 QObject 派生类型（请参阅 Final Contest 对此案例的回答）
First of all, you need to register your type to be part of QVariant managed types
首先，您需要将您的类型注册为 QVariant 托管类型的一部分
//customtype.h
class CustomType {
};
Q_DECLARE_METATYPE(CustomType)
Then you can retrieve your custom type from QVariantin this way :
然后您可以通过QVariant以下方式检索您的自定义类型：
CustomType ct = myVariant.value<CustomType>();
which is equivalent to:
这相当于：
CustomType ct = qvariant_cast<CustomType>(myVariant);
回答by lpapp
You could try using qvariant_castand qobject_cast.
您可以尝试使用qvariant_cast和qobject_cast。
QObject *object = qvariant_cast<QObject*>(selectItem);
Category *category = qobject_cast<Category*>(object);
Also, never put any persistent statement into Q_ASSERT. It will not be used when the assert is not enabled.
此外，永远不要将任何持久性语句放入 Q_ASSERT。未启用断言时不会使用它。
