Question:

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<ul><li> <a href="/questions/1368584/what-does-the-q-object-macro-do-why-do-all-qt-objects-need-this-macro" dir="ltr" rel="nofollow">What does the Q_OBJECT macro do? Why do all Qt objects need this macro?</a> <span class="question-originals-answer-count"> 5 answers </span> </li> </ul>

I am trying to connect a signal to a slot. The project compiles fine, but at runtime I get this error:

QObject::connect: No such slot QHeaderView::onFilterAdded(int)

here is my code:

class MySortFilterProxyModel: public QSortFilterProxyModel { Q_OBJECT public: explicit MySortFilterProxyModel(QObject *parent = 0); ~MySortFilterProxyModel(); void addFilter(int col, SteFilter *pFilter); void removeFilter(int col); signals: void filterAdded(int); void filterRemoved(int); } class MyHeaderView: public QHeaderView { public: MyHeaderView(); void paintSection(QPainter *painter, const QRect &rect, int logicalIndex) const; public slots: void onFilterAdded(int); void onFilterRemoved(int); private: QList<int> m_listFilters; };

I use this line of code to connect the signal to the slot:

QObject::connect(&m_proxyModel, SIGNAL(filterAdded(int)), &m_headerView, SLOT(onFilterAdded(int)));

m_proxyModel is of type MySortFilterProxyModel and m_headerView is of type MyHeaderView. They are not pointers.

I don't get why this happens. I have connected other signals and slots using the same technique and had no problems. Any help would be appreciated, thanks.

The class <em>MyHeaderView</em> doesn't have Q_OBJECT macro, don't forget to <em>run qmake</em> after you add it and only after that build your project.