QObject::connect: Cannot queue arguments of type 'std::string' (Make sure 'std::string' is registered using qRegisterMetaType().)

reddy9pp

I encounter this error when doing Signal-Slot method.

QObject::connect: Cannot queue arguments of type 'std::string'
(Make sure 'std::string' is registered using qRegisterMetaType().)

How could I resolve this?

J.Hilk

@reddy9pp
like the error says, register it to the methadones system via qRegisterMetaType or easier, use QString

reddy9pp

@J-Hilk

mainWindow.h

public:
    void  A(std:string data);
signals:
    void dataReceived(std:string data);
private slots:
    void B(std:string data);
private:
    Ui::MainWindow *ui;

How could I do this without the use of QString?
I also have to implement for cv::Mat type data

Pl45m4

@reddy9pp

How to register metatypes is explained here. Look at the Block - example.
https://doc.qt.io/qt-5/custom-types.html#creating-and-destroying-custom-objects

VRonin

@reddy9pp said in QObject::connect: Cannot queue arguments of type 'std::string' (Make sure 'std::string' is registered using qRegisterMetaType().):

I also have to implement for cv::Mat type data

Be very careful as cv::Mat is not implicitly shared, it is just shared (i.e. a copy of a cv::Mat object will point to the same data as the copied from item) so it might cause problems if you try to queue arguments of that tipe