Qt设置右键菜单无效customContextMenuRequested(const QPoint &pos)

问题代码：

cpp 复制代码

void MainWindow::onCustomContextMenuRequested(const QPoint &pos)
{
    QTreeWidgetItem *item = ui->treeWidget->itemAt(pos);
    if (item)
    {
        QMenu menu(ui->treeWidget);
        TreeNodeType nodeType = (TreeNodeType)item->data(0, Qt::UserRole + 1).toInt();
        if (nodeType == NODE_CONNECTION)
        {
            QAction actionOpen("打开连接", ui->treeWidget);
            connect(&actionOpen, &QAction::triggered, this, &MainWindow::onOpenConnectionTriggered);
            menu.addAction(&actionOpen);
            QAction actionModify("编辑连接", ui->treeWidget);
            connect(&actionModify, &QAction::triggered, this, &MainWindow::onModifyConnectionTriggered);
            menu.addAction(&actionModify);
        }
        else if (nodeType == NODE_DATABASE)
        {
            qDebug() << "NODE_DATABASE";
            QAction actionOpen("打开连接", ui->treeWidget);
            connect(&actionOpen, &QAction::triggered, this, &MainWindow::onOpenConnectionTriggered);
            menu.addAction(&actionOpen);
        }
        else if (nodeType == NODE_TABLE)
        {
            qDebug() << "NODE_TABLE";
            QAction actionOpen("打开连接", ui->treeWidget);
            connect(&actionOpen, &QAction::triggered, this, &MainWindow::onOpenConnectionTriggered);
            menu.addAction(&actionOpen);
        }

        qDebug() << "why?";
        menu.exec(QCursor::pos());
    }
}

想着先声明QMenu然后根据右键的不同类型节点弹出不一样的菜单，结果这样一直无法显示菜单。调试发现代码是按照预想的逻辑走的，后面想起一种可能：QAction在if里面定义，离开if的时候，QAction对象已经被释放掉了。然后把代码改成下面这样：

cpp 复制代码

void MainWindow::onCustomContextMenuRequested(const QPoint &pos)
{
    QTreeWidgetItem *item = ui->treeWidget->itemAt(pos);
    if (item)
    {
        TreeNodeType nodeType = (TreeNodeType)item->data(0, Qt::UserRole + 1).toInt();
        if (nodeType == NODE_CONNECTION)
        {
            QMenu menu(ui->treeWidget);
            QAction actionOpen("打开连接", ui->treeWidget);
            connect(&actionOpen, &QAction::triggered, this, &MainWindow::onOpenConnectionTriggered);
            menu.addAction(&actionOpen);
            QAction actionModify("编辑连接", ui->treeWidget);
            connect(&actionModify, &QAction::triggered, this, &MainWindow::onModifyConnectionTriggered);
            menu.addAction(&actionModify);
            menu.exec(QCursor::pos());
        }
        else if (nodeType == NODE_DATABASE)
        {
            QMenu menu(ui->treeWidget);
            qDebug() << "NODE_DATABASE";
            QAction actionOpen("打开连接", ui->treeWidget);
            connect(&actionOpen, &QAction::triggered, this, &MainWindow::onOpenConnectionTriggered);
            menu.addAction(&actionOpen);
            menu.exec(QCursor::pos());
        }
        else if (nodeType == NODE_TABLE)
        {
            QMenu menu(ui->treeWidget);
            qDebug() << "NODE_TABLE";
            QAction actionOpen("打开连接", ui->treeWidget);
            connect(&actionOpen, &QAction::triggered, this, &MainWindow::onOpenConnectionTriggered);
            menu.addAction(&actionOpen);
            menu.exec(QCursor::pos());
        }
    }
}

再次运行，果然没问题了，又学到了。