Get inherited QTreeWidgetItem

[Mihaill]

Hi!
I inherited in QTreeWidgetItem and set this item to QTreeWidget. How I can get MyTreeWidgetItem from QTreeWidget in signal currentItemChanged and function currentItem()?

class MyTreeWidgetItem : public QObject, public QTreeWidgetItem
{
    Q_OBJECT
public:
    MyTreeWidgetItem(){};
    int id = -1;
    int type = TypeItemProtocol::protocol;
    QVector <int> vector;
    void setId(int value){id = value;}
    int  getId(){return id;}
    void setType(int typeValue) {type = typeValue;}
    int  getType() {return type;}
    void addInVector(int value) {vector.append(value);}
};

[jsulm]

@Mihaill Simply cast QTreeWidgetItem* to MyTreeWidgetItem*

[Mihaill]

It is work

void MainWindow::on_treeWidgetSession_currentItemChanged(QTreeWidgetItem *current, QTreeWidgetItem *previous)
{
    MyTreeWidgetItem* item = static_cast<MyTreeWidgetItem*>(current);

[jsulm]

@Mihaill You should always check pointers after casts! If cast fails because the object is not MyTreeWidgetItem you will get nullptr and your app will crash if you try to use it.

[Christian Ehrlicher]

@jsulm said in Get inherited QTreeWidgetItem:

You should always check pointers after casts!

... and use the correct cast - static_cast<> is very problematic here since you can't huarantee that every item is a MyTreeWidgetItem here. Use dynamic_cast<> or qobject_cast<>

[JonB]

@jsulm said in Get inherited QTreeWidgetItem:

If cast fails because the object is not MyTreeWidgetItem you will get nullptr

True for dynamic_cast<>. The only time OP's static_cast<> would return nullptr is if QTreeWidgetItem *current == nullptr, not if it were say plain QTreeWidgetItem *. Just saying.....

[JonB]

@Christian-Ehrlicher said in Get inherited QTreeWidgetItem:

or qobject_cast<>

=> qobject_cast<MyTreeWidgetItem*>(current);

Here MyTreeWidgetItem is QObject but current's formal type is QTreeWidgetItem, which is not QObject. In this situation is qobject_cast<> allowed?