c++ - cpp Qt Model not updating QML view -

i using custom model qml view , want able move items drag , drop. use list in cpp model set data , bind model qml view.

however, when drop item in new position, the view ask model move item on new position. in purpose, update datalist function datalist.move(oldindexposition, newindexposition). my datalist correctly updated doesn't refresh qml view. tried use signal emit datachanged()but still not refreshing view.

i don't understand should do, suggestion ?

here simple example of try do. notice there no drag , drop here, in order make easier understand:

public:     q_invokable void move(int oldindex, int newindex) {               datalist.move(oldindex,newindex);               emit datachanged(this->index(oldindex),this->index(newindex));     }  signals:     void datachanged(const qmodelindex & topleft, const qmodelindex & bottomright); 

model.h

int main(int argc, char ** argv) {     qguiapplication app(argc, argv);      model model;     model.addsomedata("data1");     model.addsomedata("data2");     model.addsomedata("data3");      qquickview view;     view.setresizemode(qquickview::sizerootobjecttoview);     qqmlcontext *ctxt = view.rootcontext();     ctxt->setcontextproperty("mymodel", &model);      view.setsource(qurl("qrc:view.qml"));     view.show();      return app.exec(); } 

main.cpp

listview {     width: 200; height: 250      model: mymodel     delegate: text { text: "data " + data  }      mousearea {         anchors.fill: parent         cursorshape: qt.pointinghandcursor         onclicked: {             mymodel.move(0,2) //just test         }     } } 

myqml.qml

if have idea of doing wrong, kind of me! thank much.

i assume model implementation of qabstractitemmodel. in case, should call qabstractitemmodel::beginmoverows before start moving data , qabstractitemmodel::endmoverows finalise it.

q_invokable void move(int oldindex, int newindex) {     qmodelindex parent;     beginmoverows(parent, oldindex, oldindex, parent, newindex);     datalist.move(oldindex,newindex);     endmoverows(); }