Qt Quick SelectionDialog with dynamic content from C++

[oskari.petas]

Hi,

I'm addressing a problem trying to have user select an item with selectiondialog. My app works with network so, that a network request starts when user presses a button and when it returns, it will get parsed. If the parsing finds out that there is multiple choises, it signals that a selectiondialog should be shown.

The problem I have is that the Dialog is empty. Here's my QML:
//in MainPage.qml

SelectionDialog {
        function showPlaceDialog(){
            console.log("Multiple dialogs called")
            placeDialog.model = myClass.getPossibleListTo()
            placeDialog.open()
        }
        Connections {
            target: reittiopas
            onMultipleChoicesForLocationSignal: placeDialog.showPlaceDialog()
        }
        id: placeDialog
    }

With the function getPossibleListTo() returns a QList<AddressContainer *>

Q_INVOKABLE QList<AddressContainer *> getPossibleListFrom();

Where AddressContainer derives from QObject and is basicly a struck-class.

I don't fully understand why the dialog is empty. With Q_PROPERTY I should be able to access variables within AddressContainer and with a delegate of my own to visualize it? Or is there simply a better way to make a SelectionsDialog. I guess it says that is supports types that are compatible with ListView which basicly means that for my own class it has to derive from QAbstractListModel but I couldn't get that to work and that seems a bit overkill for this simple task.

Almost all examples handle a case where a dialog content is static and it can be registered with setContentProperty to use as a model, but I guess that cannot be the case now.

Thanks already for ideas!

[vladest]

its makes sense for you to read about qml data binding. especially about what kind of c++ classes supported by qml as data models

[oskari.petas]

I've read it but I it handles about the case with a custom C++ class but I believe static content registered via setContentProperty

[vladest]

but anyway that static comtent have to be surrounded by special class, derrived from QObject

[mahbub_s60]

HI,
If you try like this it will work
QStringList dataList;
dataList.append("Item 1");
dataList.append("Item 2");
dataList.append("Item 3");
dataList.append("Item 4");




QScopedPointer<QmlApplicationViewer> viewer(QmlApplicationViewer::create());

QDeclarativeContext *ctxt = viewer->rootContext();
ctxt->setContextProperty("myModel", QVariant::fromValue(dataList));

in qml
SelectionDialog {
id: dialog1
titleText: "Select team:"

model : myModel // mymodel is in CPP file

onAccepted:
{
mytext.text=dialog1.model[selectedIndex]
}
}
MouseArea
{
anchors.fill: parent
onClicked:
{
console.log("hi")
dialog1.open()
}
}

[oskari.petas]

So what am I doing wrong here. I made out the simplemost example of what I figured could work but it displays a blank list only.

// main.cpp
#include "qmlapplicationviewer.h"
#include <QDeclarativeView>
#include <QtDeclarative>

#include "testclass.h"

Q_DECL_EXPORT int main(int argc, char *argv[])
{
    QApplication app(argc,argv);

    QDeclarativeView view;
    thirdObject k;
    view.rootContext()->setContextProperty("k", &k);
    view.setSource(QUrl::fromLocalFile("qml/dialogtest/main.qml"));

    view.show();

    return app.exec();
}

//testclass.h
#ifndef TESTCLASS_H
#define TESTCLASS_H

#include <QObject>
#include <QAbstractListModel>


class myObject : public QObject
{
    Q_OBJECT
public:
    explicit myObject(QString arvo,QObject *parent = 0);
    QString arvo;
private:


};


class mylist : public QAbstractListModel
{
    Q_OBJECT
public:
    explicit mylist(QObject *parent = 0);
    QVariant data(const QModelIndex &index, int role) const;
    Qt::ItemFlags flags(const QModelIndex &index) const;
    int rowCount(const QModelIndex &parent) const;

    void addObject(myObject* obj);
    
signals:
    
public slots:
    
private:
    QList<myObject*> lista;
};

class thirdObject : public QObject
{
    Q_OBJECT
public:
    explicit thirdObject(QObject *parent=0);
    Q_INVOKABLE mylist* getList();

signals:
    void showSelections();

};

#endif // TESTCLASS_H

//testclass.cpp
#include "testclass.h"


QVariant mylist::data(const QModelIndex &index, int role) const
{
    if (!index.isValid()){
        return QVariant();
    }
    if(role == Qt::DecorationRole){
        return lista[index.row()]->arvo;
    }
    return QVariant();
}

Qt::ItemFlags mylist::flags(const QModelIndex &index) const
{
    if(index.isValid()) return (Qt::ItemIsEnabled | Qt::ItemIsSelectable);
    return Qt::ItemIsEnabled;
}

int mylist::rowCount(const QModelIndex &parent) const
{
    if(!parent.isValid())
        return 0;
    else
        return lista.size();
}

myObject::myObject(QString arvo, QObject *parent)
: arvo(arvo)
{
}

void mylist::addObject(myObject *obj)
{
    lista.append(obj);
}

thirdObject::thirdObject(QObject *parent)
{
}

mylist *thirdObject::getList()
{
    mylist *lista = new mylist;
    myObject *yksi = new myObject("oskari");
    myObject *kaksi = new myObject("antti");
    lista->addObject(yksi);
    lista->addObject(kaksi);
    return lista;
}

mylist::mylist(QObject *parent)
{
}

# main.qml
/*import QtQuick 1.1
import com.nokia.symbian 1.1

PageStackWindow {
    id: window
    initialPage: MainPage {tools: toolBarLayout}
    showStatusBar: true
    showToolBar: true

    ToolBarLayout {
        id: toolBarLayout
        ToolButton {
            flat: true
            iconSource: "toolbar-back"
            onClicked: window.pageStack.depth <= 1 ? Qt.quit() : window.pageStack.pop()
        }
    }
}*/

import QtQuick 1.1
import com.nokia.symbian 1.1

Page {
    id: mainPage
    Text {
        anchors.centerIn: parent
        text: qsTr("Hello world!")
        color: platformStyle.colorNormalLight
        font.pixelSize: 20
    }
    SelectionDialog {
        function showPlaceDialog(){
            console.log("Multiple dialogs called")
            placeDialog.model = k.getList();
           // var list = reittiopas.getPossibleListTo()
            //console.log(list.rowCount())
            placeDialog.open()


        }
        Connections {
            target: k
            onShowSelections: placeDialog.showPlaceDialog()
        }
        id: placeDialog
        //delegate: addressDelegate
    }
    Button {
        text: "Test"
        onClicked: placeDialog.showPlaceDialog()
    }
}

[vladest]

There is some workaround required for SelectionDialog
see, how its implemented on my side:

#ifndef QSTRINGLISTMODELQML_H
#define QSTRINGLISTMODELQML_H

#include <QObject>
#include <QStringListModel>

class QStringListModelQML : public QStringListModel
{
Q_OBJECT

public:
Q_PROPERTY(int count READ count NOTIFY countChanged)
// Contrary to normal QStringListModel, this class does not
// allow giving the strings in the model in constructor.
// The reason is that for this model to work also on
// MeeGo/Harmattan, the strings must be set after the
// QML template has been loaded. Otherwise the signal
// handlers in QML have not been registered. The default
// role name used to display the roles is "name", which is
// used both by Symbian and Harmattan Qt Compontents.
QStringListModelQML(const QByteArray &displayRoleName = "name", QObject *parent = 0);

// Overrides QStringListModel's function. Setting this will
// emit stringAdded(QString) for each string in the list. If
// there was non empty string list set to this model before,
// stringsReset() signal is emitted before
// stringAdded(QString) signals.
void setStringList(const QStringList &strings);
QVariant data(const QModelIndex &index, int role) const;
Q_INVOKABLE int rowCount(const QModelIndex &parent) const;
Q_INVOKABLE int columnCount(const QModelIndex & parent = QModelIndex()) const;
int count() const;
Q_INVOKABLE QVariant getSelected(int i) const;
Q_INVOKABLE QVariant data(int index) const;

signals:
void countChanged();
};

#endif // QSTRINGLISTMODELQML_H

#include "qstringlistmodelqml.h"
#include <QtCore/QHash>
#include <QtCore/QDebug>
#include <QtCore/QVariant>
#include <QtCore/QModelIndex>

QStringListModelQML::QStringListModelQML(const QByteArray &displayRoleName, QObject *parent)
: QStringListModel(parent)
{
QHash<int, QByteArray> roleNames;
roleNames.insert(Qt:isplayRole, displayRoleName);
setRoleNames(roleNames);
}

int QStringListModelQML::count() const
{
return stringList().count();
}

QVariant QStringListModelQML::getSelected(int i) const
{
qDebug() << "get" << i;
if (i >= 0 && i < count())
{
return QVariant(stringList().at(i));
}
return QVariant();
}

QVariant QStringListModelQML::data(int index) const
{
qDebug() << "data" << index;
if (index >= 0 && index < count())
{
return stringList().at(index);
}
return QVariant();
}

void QStringListModelQML::setStringList(const QStringList &strings)
{
QStringListModel::setStringList(strings);
emit countChanged();
}

int QStringListModelQML::columnCount(const QModelIndex & parent) const
{
return 1;
}

int QStringListModelQML::rowCount(const QModelIndex &parent) const
{
//qDebug() << "rowCount" << stringList().count();
return stringList().count();
}

QVariant QStringListModelQML::data(const QModelIndex &index, int role) const
{
//qDebug() << index << role;
if (index.isValid())
{
return QStringListModel::data(index, role);
}
return QVariant();
}

and usage...
QML:

SelectionDialog {
id: langdlg
width: parent.width
height: parent.height
titleText: qsTranslate("CarVCR","Select Language")
model: languageModel
selectedIndex: languageIndex
onAccepted: {
languageIndex = langdlg.selectedIndex
languageSignal(languageIndex)
language = languageModel.getSelected(langdlg.selectedIndex)
}

}

and C++:

//creating model
QStringListModelQML langsModel;
//set model to qml
qmlengine->rootContext()->setContextProperty("languageModel", &langsModel);
//put data into model
langsModel.setStringList(langs);

dont forget about model's scope

[oskari.petas]

Could similar behaviour be achieved without this line:

qmlengine->rootContext()->setContextProperty("languageModel", &langsModel);

I've tried to work around by registering my type first (qmlRegisterType() ) but I can't get that to work either..

[vladest]

hi Oskari

what the problem with the line?

[oskari.petas]

As said, if in anyway possible I would like to create the instance of the list only via a function call. Your method requires me to set the instance as a context property before I load the QML and start displaying stuff to user. But what I originally need (I will soon change my architecture, because this seems very hard) is to create a list and possibly only register the type? But most of all I would like to have info on how the selectionDialog actually works and what data types it is able to read at all?

[oskari.petas]

mahbub_s60: I couldn't get your code to work either. It throws an error: "Unable to assign QVariantList to QDeclarativeListModel*" on model : myModel // mymodel is in CPP file.
So this implicates that the list should actually be a QDeclarativeListModel* ? I wonder how could I contact the QML developers themselves..

[mahbub_s60]

Hi

I tried this one (not really optimum code) and looks work in my side with C7 Belle SW.

[vineet.jain]

Are list items visible in a simple listview , if you try to use one in the qml file?

[oskari.petas]

vineet.jain: No I couldn't
mahbub_s60: I noticed you have also tried qmlRegisterType sort of thing. Did you ever get that to work?

[mahbub_s60]

The example I put work in my machine Symbian Belle C7 device, it doe not work in your side?