How to access list property of C++ object in QML

strasidlo

Hello, I have started to learn the Qt 5 and got stuck at one point for a long time.

I have two classes. ScoreHandler handles a list of ScoreRecords. I create those two classes in C++ and set an instance of ScoreHandler as a context property. Now in QML I can assign the model, but the delegate can not see properties of ScoreRecord. Do I have to register something somewhere? Please help me.

scorerecord.h
@
class ScoreRecord : public QObject
{
Q_OBJECT

Q_PROPERTY(QString name READ name WRITE setName NOTIFY nameChanged)
Q_PROPERTY(QString date READ date WRITE setDate NOTIFY dateChanged)
Q_PROPERTY(QString score READ score WRITE setScore NOTIFY scoreChanged)

public:
ScoreRecord(QObject *parent = 0);
ScoreRecord(const QString& n, const QString &d, const QString &s, QObject *parent = 0);
QString name() const;
void setName(const QString &str);
QString date() const;
void setDate(const QString &str);
QString score() const;
void setScore(const QString &str);

signals:
void nameChanged();
void dateChanged();
void scoreChanged();

public slots:

private:
QString m_name;
QString m_date;
QString m_score;
};
@

scorehandler.h

@
class ScoreHandler : public QObject
{
Q_OBJECT
private:
const char* SCORE_TABLE_FILENAME;

struct scoreRow {
    char name[128];
    char date[32];
    char score[16];
};

public:
explicit ScoreHandler(QObject *parent = 0);
QList<ScoreRecord *> scoreList;

signals:

public slots:
void SaveScore(const QString &name, const QString &date, const QString &score);
void LoadScore();
};
@

main.c
@
int main(int argc, char *argv[])
{

QGuiApplication app(argc, argv);
QtQuick2ApplicationViewer viewer;

ScoreHandler* scoreHandler = new ScoreHandler();
QQmlContext* ctx = viewer.rootContext();
ctx->setContextProperty("MyScoreModel", QVariant::fromValue(scoreHandler->scoreList));
viewer.setMainQmlFile&#40;QStringLiteral("qml/qmlListView/main.qml"&#41;&#41;;

viewer.showExpanded(&#41;;

return app.exec&#40;&#41;;

}
@

QML file
@
import QtQuick 2.0

Rectangle {
width: 360
height: 360

ListView {
    width: 100; height: 100
    anchors.fill: parent

    model: MyScoreModel
    delegate: Text {
        text: name    // Here the JS interpreter prints error: ReferenceError: name is not defined
    }
}

}
@

And please can somebody explain me, why the following code works? What is the reason?

main.c
@
int main(int argc, char *argv[])
{

QGuiApplication app(argc, argv);
QtQuick2ApplicationViewer viewer;

QList<QObject *> scoreList;

scoreList.append(new ScoreRecord("Jmeno1", "datum1", "score1"));
scoreList.append(new ScoreRecord("Jmeno2", "datum2", "score2"));
scoreList.append(new ScoreRecord("Jmeno3", "datum3", "score3"));

QQmlContext* ctx = viewer.rootContext();
ctx->setContextProperty("MyScoreModel", QVariant::fromValue(scoreList));
viewer.setMainQmlFile&#40;QStringLiteral("qml/qmlListView/main.qml"&#41;&#41;;

viewer.showExpanded(&#41;;

return app.exec(&#41;;

}
@

stevenceuppens

Hi,

In your code examples above, you forgot to show the code of scorehandler.h, it's twice the source code of scorerecord.h.

can you first update it? than i will have a look at it.

Rgds,

strasidlo

Sorry, I have updated it.

stevenceuppens

in class ScoreHandler you have the variable

QList<ScoreRecord *> scoreList;

which you expose to QML, ScoreRecord is derived from QObject, but QML does not handle inheritance for this,

so change line 16 to QList<QObject *> scoreList;

other things seems ok...

alternatively, instead of using the QList<QObject*> style, you can create a real QAbstractItemModel.

strasidlo

Ahaaa, that was the thing. Thank you very much. I will do some experiments with QAbstractItemModel later and probably will come back with another problems. So far, thank you gain.

terenty

Hi, See examples\quick\models\abstractitemmodel in your Qt installation for an example on custom QAbstractItemModel