Modify c++ model data from QML Repeater

[laszlo.gosztola]

Hi all!

I would like to create something similar to the corkboard qml example. On a screen I have some items, which I can move, resize, rotate, and I can store these properties.

I created a model inherited from QAbstractListModel on C++ side. It populates data well.

On the QML side I show it in a Repeater, like this:

Repeater {
  id: myRepeater
  model: dayScreenModel
  DayScreenEntry {
    x: position.x
    y: position.y
    text: title
}

Repeater {
  id: myRepeater
  model: dayScreenModel
  DayScreenEntry {
    x: position.x
    y: position.y
    text: title
}

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position, title, size, rotation comes from the C++ model.

It works fine.

But how can I achieve modification of these data?

I found a way:
in the model, created a public slot:
void updateData(int index, QString role, QVariant value);

and, in the DayScreenEntry.qml I can call like this:
myRepeater.model.updateData(index, "title", "NewTitle")

I can refresh the data in code, and it populates also to the qml side, shows the changes.

But, I have some problems with it:
- it's not 'elegant' - Is it possible somehow to call the 'setData' function of the model?
- on QML side, i have to write the model name in the delegate - I can use it only for this model, have to know the model name.

Do You know any other way to get this stuff working?

[wysota]

Since the delegate is a component, it should be possible to have it contain an item that allows you to edit the content it displays (like the TextEdit element). If you bind the model's property to a property that is editable by the component, there is a good chance the change will be propagated to the model.

[laszlo.gosztola]

Hello!

Thank You for your reply. I want expect what you write. But I don't know, how...

I attach a simple example.
The interesting part is in the qml file's mousearea section. I can reach the index, and the title also... But I cannot change the title
Maybe only I forgot to set a flag or something like this.
I think, that 'setData' should be called somehow as when the data populates from the model to the view - it's achieved by the 'data' function.
QmlModel.zip

main.cpp

#include <QApplication>
#include <QMessageBox>
 
#include "mainwidget.h"
 
int main(int argc, char** argv)
{
    QApplication a (argc, argv);
 
    MainWidget* mainWidget=new MainWidget();
    mainWidget->show();
    int r=0;
    try
    {
	r=a.exec();
    }catch (...)
    {
	QMessageBox::critical(NULL, QObject::tr("Error"), QObject::tr("Critical error - Unhandled exception in the application!"));
	r=-1;
    }
    delete mainWidget;
    return r;
}

#include <QApplication>
#include <QMessageBox>

#include "mainwidget.h"

int main(int argc, char** argv)
{
    QApplication a (argc, argv);

    MainWidget* mainWidget=new MainWidget();
    mainWidget->show();
    int r=0;
    try
    {
	r=a.exec();
    }catch (...)
    {
	QMessageBox::critical(NULL, QObject::tr("Error"), QObject::tr("Critical error - Unhandled exception in the application!"));
	r=-1;
    }
    delete mainWidget;
    return r;
}

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mainwidget.h

#ifndef MAINWIDGET_H
#define MAINWIDGET_H
 
#include <QtDeclarative/QDeclarativeView>
#include "dummymodel.h"
 
 
class MainWidget : public QDeclarativeView
{
    Q_OBJECT;
public:
    MainWidget(QWidget* parent=0);
    ~MainWidget();
public slots:
 
 
private:
    QDeclarativeContext* m_context;
    DummyModel model;
 
};
 
#endif // MAINWIDGET_H

#ifndef MAINWIDGET_H
#define MAINWIDGET_H

#include <QtDeclarative/QDeclarativeView>
#include "dummymodel.h"


class MainWidget : public QDeclarativeView
{
    Q_OBJECT;
public:
    MainWidget(QWidget* parent=0);
    ~MainWidget();
public slots:


private:
    QDeclarativeContext* m_context;
    DummyModel model;

};

#endif // MAINWIDGET_H

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mainwidget.cpp

#include "mainwidget.h"
 
#include <QtDeclarative>
#include <QDeclarativeContext>
 
MainWidget::MainWidget(QWidget* parent) : QDeclarativeView(parent)
{
    setResizeMode(QDeclarativeView::SizeRootObjectToView);
    setMinimumSize(300,300);
 
    m_context=rootContext();
    m_context->setContextProperty("dummyModel", &model);
    setSource(QUrl("qml/qmlModel/main.qml"));
}
 
MainWidget::~MainWidget()
{
 
}

#include "mainwidget.h"

#include <QtDeclarative>
#include <QDeclarativeContext>

MainWidget::MainWidget(QWidget* parent) : QDeclarativeView(parent)
{
    setResizeMode(QDeclarativeView::SizeRootObjectToView);
    setMinimumSize(300,300);

    m_context=rootContext();
    m_context->setContextProperty("dummyModel", &model);
    setSource(QUrl("qml/qmlModel/main.qml"));
}

MainWidget::~MainWidget()
{

}

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dummymodel.h

#ifndef DUMMYMODEL_H
#define DUMMYMODEL_H
 
#include <QAbstractListModel>
#include <QStringList>
 
class DummyModel : public QAbstractListModel
{
    Q_OBJECT
public:
    enum DummyRoles {
	TitleRole=Qt::UserRole+1
    };
 
    DummyModel(QObject* parent=NULL);
    ~DummyModel();
 
    int rowCount(const QModelIndex &parent) const;
    QVariant data(const QModelIndex &index, int role) const;
    bool setData(const QModelIndex &index, const QVariant &value, int role);
 
private:
 
    void fillData();
    QStringList m_data;
};
 
#endif // DUMMYMODEL_H

#ifndef DUMMYMODEL_H
#define DUMMYMODEL_H

#include <QAbstractListModel>
#include <QStringList>

class DummyModel : public QAbstractListModel
{
    Q_OBJECT
public:
    enum DummyRoles {
	TitleRole=Qt::UserRole+1
    };

    DummyModel(QObject* parent=NULL);
    ~DummyModel();

    int rowCount(const QModelIndex &parent) const;
    QVariant data(const QModelIndex &index, int role) const;
    bool setData(const QModelIndex &index, const QVariant &value, int role);

private:

    void fillData();
    QStringList m_data;
};

#endif // DUMMYMODEL_H

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dummymodel.cpp

#include "dummymodel.h"
 
#include <QDateTime>
 
DummyModel::DummyModel(QObject *parent) : QAbstractListModel(parent)
{
    m_data.clear();
    QHash<int, QByteArray> roles;
    roles[TitleRole]="title";
    setRoleNames(roles);
    fillData();
}
 
DummyModel::~DummyModel()
{
 
}
 
int DummyModel::rowCount(const QModelIndex &parent) const
{
    return m_data.count();
}
 
QVariant DummyModel::data(const QModelIndex &index, int role) const
{
    qDebug("dummymodel::data");
    qDebug("Role: %d", role);
    if (!index.isValid()) return QVariant();
    if ((index.row()<0) || (index.row()>=m_data.count())) return QVariant();
    if (role==TitleRole)
	return m_data.at(index.row());
    return QVariant();
}
 
void DummyModel::fillData()
{
    qsrand(QDateTime::currentMSecsSinceEpoch());
    beginResetModel();
    m_data.clear();
    int num=1+qrand()%8;
    for (int i=0; i<num; i++)
    {
	m_data.append(QString("DummyText%1").arg(i+1));
    }
    endResetModel();
}
 
bool DummyModel::setData(const QModelIndex &index, const QVariant &value, int role)
{
    qDebug("SetData called");
    return true;
}

#include "dummymodel.h"

#include <QDateTime>

DummyModel::DummyModel(QObject *parent) : QAbstractListModel(parent)
{
    m_data.clear();
    QHash<int, QByteArray> roles;
    roles[TitleRole]="title";
    setRoleNames(roles);
    fillData();
}

DummyModel::~DummyModel()
{

}

int DummyModel::rowCount(const QModelIndex &parent) const
{
    return m_data.count();
}

QVariant DummyModel::data(const QModelIndex &index, int role) const
{
    qDebug("dummymodel::data");
    qDebug("Role: %d", role);
    if (!index.isValid()) return QVariant();
    if ((index.row()<0) || (index.row()>=m_data.count())) return QVariant();
    if (role==TitleRole)
	return m_data.at(index.row());
    return QVariant();
}

void DummyModel::fillData()
{
    qsrand(QDateTime::currentMSecsSinceEpoch());
    beginResetModel();
    m_data.clear();
    int num=1+qrand()%8;
    for (int i=0; i<num; i++)
    {
	m_data.append(QString("DummyText%1").arg(i+1));
    }
    endResetModel();
}

bool DummyModel::setData(const QModelIndex &index, const QVariant &value, int role)
{
    qDebug("SetData called");
    return true;
}

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and the qml file:
main.qml

import QtQuick 1.0
 
 
Rectangle {
    id: base
    width: 500
    height: 360
    Repeater {
	model: dummyModel
	delegate: myDelegate
    }
 
    Component {
	id: myDelegate
	Rectangle {
	    x: 10
	    y: index*35+10
	    width: 200
	    height: 30
	    color: "yellow"
	    TextEdit {
		text: title
		font.pointSize: 18
	    }
	    MouseArea {
		anchors.fill:  parent
		onClicked: {
		    console.log("Clicked index:",index);
		    title="test"
		}
	    }
	}
    }
}

import QtQuick 1.0


Rectangle {
    id: base
    width: 500
    height: 360
    Repeater {
	model: dummyModel
	delegate: myDelegate
    }

    Component {
	id: myDelegate
	Rectangle {
	    x: 10
	    y: index*35+10
	    width: 200
	    height: 30
	    color: "yellow"
	    TextEdit {
		text: title
		font.pointSize: 18
	    }
	    MouseArea {
		anchors.fill:  parent
		onClicked: {
		    console.log("Clicked index:",index);
		    title="test"
		}
	    }
	}
    }
}

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[wysota]

Try implementing flags() for your model and return ItemIsEditable.

[laszlo.gosztola]

Already tried.

Qt::ItemFlags DummyModel::flags(const QModelIndex &index) const
{
    qDebug("DummyModel::Flags");
    return Qt::ItemIsEditable;
}

Qt::ItemFlags DummyModel::flags(const QModelIndex &index) const
{
    qDebug("DummyModel::Flags");
    return Qt::ItemIsEditable;
}

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But unfortunately it doesn't help, but even the function is not called. (No qDebug output)

[wysota]

You have to return other flags as well.Like ItemIsEnabled. Make sure the signature fits and verify using QListView that your model is editable.

[laszlo.gosztola]

It is a good idea to test also with a QListView...

I found that the behavior is a little different.
From QML the flags function never called. In the data function the role is just the roles I have defined with setRoleNames call.

If I use a form with QListView flags is called many times, and role is DisplayRole, and others, so I had to extend the model, to implement the displayrole also.

But from QML, the answer is always: Cannot assign to read-only property 'title'

Any other idea?

Maybe I should use the solution with calling the slots...

[Matriarch]

I am also trying to use QAbstractItemModel::setData from QML, but it is not possible. QML model-view-controller connection with C++ Qt is build-in hardcoded suck, thats all.