Not able to pass data from C++ to QML

SteMMo

Hi everybody.
I'm not able to pass some objects list to QML and I don't understand where is the problem.
Windows + Qt 5.7.1
I defined a simple object:

mymedia.cpp:

#include "mymedia.h"

MyMedia::MyMedia(QString path, int duration) : m_path(path), m_duration(duration)
{
}

QString MyMedia::path() const {
    return m_path;
}

int MyMedia::duration() const {
    return m_duration;
}

mymedia.h:

#ifndef MYMEDIA_H
#define MYMEDIA_H

#include <QObject>

class MyMedia : public QObject
{
    Q_OBJECT

    Q_PROPERTY(QString path READ path) 
    Q_PROPERTY(int duration READ duration)

public:
    MyMedia(QString path, int duration = 0);

    QString path() const;
    int duration() const;

private:
    QString m_path;
    int m_duration;

};

#endif // MYMEDIA_H

main.cpp:

QList<QObject*> contentList;
...
...
context->setContextProperty("fileDataModel", QVariant::fromValue(contentList));

main.qml:

 ListView {
            id: listView
            x: 522
            y: 8
            width: 110
            height: 160
            model: fileDataModel
            delegate: Item {
                id: itemRowFile
                x: 5
                width: 80
                height: 40
                Row {
                    id: row1
                    Rectangle {
                        width: 40
                        height: 40
                        // color: colorCode
                    }

                    Text {
                        text: "Q "+modelData.path
                        anchors.verticalCenter: parent.verticalCenter
                        font.bold: true
                    }
                    spacing: 10
                }
            }
        }

I checked that contentList is filled with my data, but the list on the screen is always empty.
Where I'm wrong?

Regards

SteMMo

Hope I finally solved ...
The problem was the line

property var fileList

in the qml file that overwrites the one (same name) passed from the C++ code.

Xyrer

@SteMMo said in Not able to pass data from C++ to QML:

context->setContextProperty("fileDataModel", QVariant::fromValue(contentList));

I've never seen that QVariant::fromValue(contentList) being used, does

context->setContextProperty("fileDataModel", &contentList);

not work?

SteMMo

I solved.
I think the problem was the id of the Row element inside the Item delegate.

SteMMo

Sorry, this is not true :(

The truth is that I can see the data if I pass them as ListView model, but I cannot see them if I pass them in a var properties.

Window {

    property var fileList

    onFileListChanged: {
        console.log("Lista:")
        for(var property in fileList)
            console.log(property)
        console.log("fine Lista")
    }

In the main source:

    context->setContextProperty("fileList", QVariant::fromValue(contentList));  // Not passed

    context->setContextProperty("fileDataModel", QVariant::fromValue(contentList));  // ok passed

SteMMo

@Xyrer If I change the code as you suggest:

    context->setContextProperty("fileList", &contentList); // QVariant::fromValue(contentList));  // ?

I have some errors:

In file included from C:\Qt\Qt5.7.1_MinGw\5.7\mingw53_32\include/QtCore/qlocale.h:43:0,
                 from C:\Qt\Qt5.7.1_MinGw\5.7\mingw53_32\include\QtGui/qguiapplication.h:46,
                 from C:\Qt\Qt5.7.1_MinGw\5.7\mingw53_32\include\QtGui/QGuiApplication:1,
                 from ..\QtComuneQml\main.cpp:9:
C:\Qt\Qt5.7.1_MinGw\5.7\mingw53_32\include/QtCore/qvariant.h: In function 'int qMain(int, char**)':
C:\Qt\Qt5.7.1_MinGw\5.7\mingw53_32\include/QtCore/qvariant.h:471:12: error: 'QVariant::QVariant(void*)' is private
     inline QVariant(void *) Q_DECL_EQ_DELETE;
            ^
..\QtComuneQml\main.cpp:60:57: error: within this context
     context->setContextProperty("fileList", &contentList); // QVariant::fromValue(contentList));  // ?

SteMMo

Hope I finally solved ...
The problem was the line

property var fileList

in the qml file that overwrites the one (same name) passed from the C++ code.

Pablo J. Rogina

@SteMMo said in Not able to pass data from C++ to QML:

Hope I finally solved ...

If so, please don't forget to mark your post as such! Thanks.