Modify c++ model data from QML Repeater

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:

Code:

---

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

---

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?

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.

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.
Attachment 5910

main.cpp

Code:

---

#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;
}

---

mainwidget.h

Code:

---

#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

---

mainwidget.cpp

Code:

---

#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()
{
 
}

---

dummymodel.h

Code:

---

#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

---

dummymodel.cpp

Code:

---

#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;
}

---

and the qml file:
main.qml

Code:

---

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"
		}
	    }
	}
    }
}

---

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

Already tried.

Code:

---

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

---

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

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

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...

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.