base class QSortFilterProxyModel has private copy constructor

mrenoch

Need help, I'm a Seasoned developer and I've been working with QML for about a year but I'm very new to C++ and I'm working on a project to convert a pyqt application to a pure C++ application. We have an app that is primarily all QML with several different sort/filter lists. In the existing pyqt app we can generate a QSortFilterProxyModel from QML and set it as the source model to any List within QML but I have so far failed to convert this functionality to a pure C++ solution. Here are the relevant code Snippets that I have so far:

::main.cpp

int main(int argc, char *argv[])
{
    QGuiApplication app(argc, argv);
    QQmlApplicationEngine engine;
    RootContext rrc;
    QQmlContext *rootContext = engine.rootContext();
    /*this lets me use a single rootContext QObject from C++ to have access to global properties and slots within the QML application*/
    rootContext->setContextObject(&rrc);

    engine.load(QUrl(QStringLiteral("(path to root .qml file)")));
    QObject *topLevel = engine.rootObjects().value(0);
    QQuickWindow *window = qobject_cast<QQuickWindow *>(topLevel);

    window->show();

    return app.exec();
}

:: rootContext.h

#include <filtermodel.h>
...
class RootContext : public QObject {
    Q_OBJECT
public:
    explicit RootContext(QObject* parent = 0);
public slots:
    // If I remove this slot from the header and the C++ then everything compiles ok
    FilterModel GetSortFilterModel(QObject *parent);
};
...

:: rootContext.cpp

#include <filtermodel.h>
...
RootContext::RootContext(QObject* parent)
    : QObject(parent)
{
}
// This method causes the compile error: base class QSortFilterProxyModel has private copy constructor
FilterModel RootContext::GetSortFilterModel(QObject *parent)
{
    return new FilterModel(parent);
}
...

:: filtermodel.h

#ifndef SORTFILTERMODEL_H
#define SORTFILTERMODEL_H

#include <QSortFilterProxyModel>


class FilterModel: public QSortFilterProxyModel
{
    Q_OBJECT
public:
    FilterModel(QObject * parent  = 0);

    ~FilterModel();

signals:

public slots:
};

#endif // SORTFILTERMODEL_H

:: filtermodel.cpp

#include "filtermodel.h"

FilterModel::FilterModel(QObject* parent): QSortFilterProxyModel(parent)
{
}

FilterModel::~FilterModel()
{
}

Then we can generate a new sortfilter model from QML which we currently do in the pyqt app all over the place like this:

Component {
        Item {
            width: parent.width
            height: childrenRect.height
            property var filteredModel:  GetSortFilterModel(gridView)
            Binding {
                target: filteredModel
                property: 'source'
                value:  (Pre-generated ListModel of items)
            }

            GridView {
                id: gridView
                model: filteredModel
                width: parent.width
                delegate: someDelegate
            }
        }
    }

compile output:
In file included from ..rootcontext.cpp:1:
In file included from ..rootcontext.h:7:
../filtermodel.h:7:7: error: base class 'QSortFilterProxyModel' has private copy constructor
class FilterModel: public QSortFilterProxyModel
^
../../../../Qt5.5/5.5/clang_64/lib/QtCore.framework/Headers/qsortfilterproxymodel.h:162:20: note: declared private here
Q_DISABLE_COPY(QSortFilterProxyModel)
^
.../Qt5.5/5.5/clang_64/lib/QtCore.framework/Headers/qglobal.h:1042:5: note: expanded from macro 'Q_DISABLE_COPY'
Class(const Class &) Q_DECL_EQ_DELETE;
^
..rootcontext.cpp:57:5: note: implicit copy constructor for 'FilterModel' first required here
return new FilterModel(parent);
^
1 error generated.
make: *** [rootcontext.o] Error 1
14:27:04: The process "/usr/bin/make" exited with code 2.
Error while building/deploying project Pumpernickel (kit: Desktop QT5.5)
When executing step "Make"

SGaist

Hi,

FilterModel RootContext::GetSortFilterModel(QObject *parent) should rather be FilterModel* RootContext::GetSortFilterModel(QObject *parent)

Otherwise you are trying to copy a QObject derived class which is not possible.

mrenoch

Thank you thank you, that totally works, It solved my compile error, I then started getting a runtime error in QML saying "unknown method return type FilterModel*" but once I regestered that type with QML its now working. Quick question, I'm currently registering that type in my main.cpp file like so:

qmlRegisterType<FilterModel>("FilterModel", 1, 0, "FilterModel");

I was just wondering if there was a way to include the type in the QML_IMPORT_PATH property or something, or if I'll just have to use the former example to register all my custom QObject types?

SGaist

You have to register your custom types