[QMenu] Context menu for widget created in Qt Creator

[Macok]

I'd like to add context menus for widgets on my form.
As I know to do that I should reimplement Widget::contextMenuEvent(QContextMenuEvent*) function.
But how can I reimplement it if widget is created in Qt Creator (designer)?

@EDIT
Ok, I found out I can do it by this way:

void QLineEdit::contextMenuEvent ( QContextMenuEvent * event ){
     QMenu *menu=new QMenu;
     (...)
     menu->exec(event->globalPos());
}

void QLineEdit::contextMenuEvent ( QContextMenuEvent * event ){
     QMenu *menu=new QMenu;
     (...)
     menu->exec(event->globalPos());
}

To copy to clipboard, switch view to plain text mode 

But is there any way to set context menu for only one lineedit?