@VRonin said in How to propagate changes in SingleTon type custom QAbstractListModel on QML ListView?:

@qml.newbie said in How to propagate changes in SingleTon type custom QAbstractListModel on QML ListView?:

m_hackNewsList.append(HackNews{id, deleted, type, by, time, text, dead, parentId, pollId, kidsIdList, url, score, title, partsIdList, descendantCount});

You need to call beginInsertRows/endInsertRows before/after m_hackNewsList.append(HackNews{id, deleted, type, by, time, text, dead, parentId, pollId, kidsIdList, url, score, title, partsIdList, descendantCount});

I have now added these lines but even now it's not working. Could be down to something I did wrong in the main.cpp where I'm registering the model for qml? The main cpp file is as below.

#include <QGuiApplication> #include <QQmlApplicationEngine> #include "NetworkRequestMaker.h" #include "HackNewsModel.h" int main(int argc, char *argv[]) { QCoreApplication::setAttribute(Qt::AA_EnableHighDpiScaling); QGuiApplication app(argc, argv); NetworkRequestMaker testRequestMaker; qmlRegisterType<HackNewsModel>("Hacknews", 1, 0, "HackNewsModel"); QQmlApplicationEngine engine; const QUrl url(QStringLiteral("qrc:/main.qml")); QObject::connect(&engine, &QQmlApplicationEngine::objectCreated, &app, [url](QObject *obj, const QUrl &objUrl) { if (!obj && url == objUrl) QCoreApplication::exit(-1); }, Qt::QueuedConnection); engine.load(url); return app.exec(); }

@JonB Thank you for your explanation. I understand what i need to do, but i need a little help in making the right signals and slots. My project was setup using the "Using C++ Models in QML {tutorial}" as a guide. here the ToDoList class is set as the data in ToDoListModel class.
In the ToDoList Calss there are:
1.appendItem() function, which emits the signals preItemAppended() and postItemAppended()
2.removeItem() funciton, which emits the signals preItemRemoved() and postItemRemoved()
[these work fine]
3.similar to the appendItem() and removeItem() I am trying to make a setItemAt() function that will modify the existing data. but there was no steps in the tutorial to indicate how i could notify the model to emit the dataChanged() signal. I tried making my own signal in the data class and a slot in model class but i couldn't figure out how to connect them. the main function has a ToDoList object but no ToDoListModel object (ToDoListModel is just registered to qml). i am only familiar with using the connect(*sender,signal,*receiver, slot) function to connect.
I suspect that it has something to do with the
'Q_PROPERTY(ToDoList *list READ list WRITE setList NOTIFY listChanged)'
line in the ToDoListModel header file. following the tutorial I removed the NOTIFY listChanged part.
summary:which signal do i need to emit from the data class(ToDoList) to have the model class (ToDoListModel) emit the dataChanged() signal?

Hi @J-Hilk vielen vielen Dank. Das hat mir sehr weitergeholfen und es funktioniert jetzt dank Deiner Hilfe.

Eine schöne neue Woche wünsche ich Dir.

Grüße
Sven

Can we finally see where and how you emit dataChanged()? And with which indexes?

Waiting for guide "How to avoid JavaScript models in Qt and why should you care" (performance, memory usage)

Indeed it works !
I did 2 mistakes, I forgot ".item" after currentItem and I didn't changed currentIndex when I switch between pages because I use positionViewAtIndex. But positionViewAtIndex don't change currentIndex of the listView.

Thanks guys !

@gabor53 If you can provide a complete example then I can see the issue first hand then as it seems like it should work, but it is hard to say without seeing it.

@GrecKo oh thank you very much. I confused bottomMargin for anchors.bottomMargin. I wasn't aware of this property being available. This is exactly what I needed!

Hi ,

you can use the SwipeView property interactive, to look when ListView are scrolling and enable in ListView when SwipeView scrolling

In this case, the color of the model item is being changed somewhere in the backend

You don't require to do this. This is where Model View framework comes into picture. color change should automatically taken care by the model itself. I'm assuming that you have written custom model. Are you sending the dataChanged(..) signal whenever data is changed at model ?

Thanks for the feedback.
I have a follow up question though.

Where are QML's default role names documented? I couldn't see the list. It would save me a lot of time. EDIT Here they are: link.

Found those three properties completely randomly on a completely unrelated topic post...

Dropping them right here, just in case someone needs it :

clip: true boundsBehavior: Flickable.DragAndOvershootBounds snapMode: ListView.SnapToItem

They're doing about everything i need. I think that's a common problem beginners fall into but there is not that much topics about it.

I am not finding the way to do this: to have ListView virtualization in all ListView usages.
Someone is able to undertand why?

@jpnurmi said in ListView and PageIndicator - PageIndicator is not updated:

The bindings are fine. The problem is that the ListView has only snapMode set, but highlightRangeMode seems to be missing. Therefore the ListView is not changing its currentIndex while flicking.

snapMode does not affect the currentIndex. To update the currentIndex as the list is moved, set highlightRangeMode to ListView.StrictlyEnforceRange.

https://doc-snapshots.qt.io/qt5-5.9/qml-qtquick-listview.html#snapMode-prop

Thank you @jpnurmi.
The following line solved the problem:

highlightRangeMode: ListView.StrictlyEnforceRange

Somehow I missed another thread: https://forum.qt.io/topic/81429/listview-does-not-change-currentindex-when-scrolling/6

@Niltava Hello,

property int _index : 4

ListView {
id: listView
width: 180; height: 200
// currentIndex: _index
Component.onCompleted : currentIndex = _index
}
like this your list will be set at index 4

@jpnurmi Thanks !!! its working

Hi,
thank you very much for your good answer,
and for the hint with the repeater, i will look for a better way to display the Items.

Thanks @jpnurmi,

This is exactly what i was looking for, all my issues are solved.

@Mathan-M
as i said when it displays a row, the model is correctly applied, so there must be something wrong with your model implementation.

@Mathan-M said in Signal emit Issue - Listview is not showing full list:

Do we have any link/tutorials to follow or how to bind the value from CPP to qml.

Here you go.

@Mathan-M You can access the attached property named index inside the delegate of ListView.

The easy way:
get rid of PortalMapItemInfo, store the values in 4 different QStringList and use a QStringListModel

The proper way:
in HomeController.h add Q_DECLARE_METATYPE(PortalMapItemInfo) http://doc.qt.io/qt-5/qmetatype.html#Q_DECLARE_METATYPE

Instead of a List store your data in a 1-column QStandardItemModel and expose it via a Q_PRPERTY

@Mathan-M Why do you want to bind to ListElement?
ListElement's are added to ListModel.
You should probably try to access this model from C++. ListModel is also a QAbstractItemModel.

Any reason why you can't use QStandardItemModel? in that case subclass QStyledItemDelegate and reimplement paint

void QStyledItemDelegate::paint(QPainter *painter, const QStyleOptionViewItem &option, const QModelIndex &index) const { Q_ASSERT(index.isValid()); QStyleOptionViewItem opt = option; initStyleOption(&opt, index); ///////////////////////////////////// // Set the background based on the content if(index.data().toInt()==1) opt.backgroundBrush = QBrush(Qt::red); ///////////////////////////////////// const QWidget *widget = option.widget; QStyle *style = widget ? widget->style() : QApplication::style(); style->drawControl(QStyle::CE_ItemViewItem, &opt, painter, widget); }

thanks @veryqtperson . I will try to implement it

@cjmdaixi
It was my understanding that this operation only needs to occur when the size of the model is being changed, i.e. when rows are being added to the structure. In this case, I simply want to access data members in the model. I will implement the begin/endInsertRows and see if it makes a difference.
It is also worth mentioning that I am able to confirm that changes are being made to the C++ model. The problem seems to be that the QML is not seeing the updates. I believe a solution would be to find a way to manually update the delegates in the ListView, but there doesn't seem to be a straightforward way to do this.

This is not a known issue. Please report a bug and we'll take a look.

Hi! Would be great if you could put together a minimal example to reproduce this and then file a bug report at bugreports.qt.io :-)

@jpnurmi Thank's a lot! That's it :) Now everything works like a charm :)

You saved my day!

@CocoJoe Welcome.
You can answer on stackoverflow)

Hello,

From the status value (which was either 1 or 2), I supposed that it had no problem findind the file.
I solved the issue by myself, the header of my XML file was missing a double quote in the version value.
Now it is working.

Regards,

@Mark81 If index is 0 then don't start the animation. Well something like:

property int myIndex : 0 function animate(idx) { listAnimation.running = false var pos = list.contentY; var destPos; list.positionViewAtIndex(idx, ListView.Beginning); destPos = list.contentY; listAnimation.from = pos; listAnimation.to = destPos; listAnimation.running = true; } Timer { ... onTriggered: { if(myIndex==0) list.positionViewAtIndex(myIndex,ListView.Beginning); else animate(myIndex) myIndex++ if(myIndex==list.count-1) myIndex = 0 } }

@Qmyo You can create a 2 Q_INVOKABLE functions. One will return the Repeater's model number and other will return ListView's models. You can make use of index attached property which can be passed to the Q_INVOKABLE functions to return particular model.