@JoeCFD said in QVariant to QList:

Understand. Thiink about you can never be number 1 anymore if you play chess.

Oddly enough, that was never a concern of mine.

@SGaist
That's What i want bro Really Thank you <3

@JonB

Huge thanks, you solved the puzzle for me!

@Gojir4 thank you so much

The problem arises from the usage of the method m_model.setStringList(). The latter always clear the previous data, hence the index always reset upon its call.

Solution:

Use m_model.setStringList() only in the constructor to init the model.

After that manually insert the row on the model and set the data for the respective row. This can be achieved with a simple modification in the slot method.

MainWindow::MainWindow(QWidget *parent) : QMainWindow(parent) , ui(new Ui::MainWindow) { ui->setupUi(this); m_model.setStringList({"1","2"}); ui->comboBox->setModel(&model); } void MainWindow::on_pushButton_clicked() { m_model.insertRow(model.rowCount()); m_model.setData(model.index(model.rowCount()-1), "3"); }

In the example above, "3" is appended to the list model without changing the current index from the QComboBox.

Hi @LeLev,

I tried your solution. Its showing the image. That is fine.
Now if i have more elements then its filling in the same space.
I need to scroll thorough the screen to see the elements.
How to do that ? How should I use Flickable in this case.

Note: For example: If the screen layout is 500x500, and each element size id 50x50,
then i should only see 16 elements initially. I have to scroll down on the screen to see the remaining elements.

@jeanmilost
I can't answer all your questions, as I'm not an expert on Qt's Model/View system, what I do know is,

that all models have a QAbstractItemModel as base model and that is also the ABI for all views.
For that reason alone, you can assign all models to all views. You will however not get a useful representation of all your data in all views.

As I understand it, and anyone fell me to correct me here, the other higher level classes of models are only there to make your life easier, as in you do not have to implement all functions/functionalities of the whole AbstractItemModel class

@daljit97 said in Unable to edit QSqlTableModel from QML:

, Qt::EditRole);

Then you should probably pass the role and not editRole, otherwise model won't know which column to update.

@Christian-Ehrlicher It caches entries that could have fairly high resolution images in them. 100MB consumed is quite reasonable for my particular use case. I've solved my problem my creating a general-purpose list model class which does not retain too many recent items in memory, and then implementing an application-specific subclass that will automatically produce small, low-resolution thumbnails and save them to a separate table to allow for faster loading later on.

On the model you are free to expose the internal structure. QStandardItemModel does it by exposing QStandardItem for example. However if you don't want to make use of the QAbstractItemModel interface and its seamless integration with views and delegate and just use your custom classes why bother subclassing a model in the first place? Just start from scratch. I'm not suggesting this is the most efficient way in terms of developer time but if performance is the only priority then feel free to go as low level as you can

After thinking about this problem more and looking at the interface for QAbstractProxyModel, I am beginning to think that a subclass of a proxy model is not the answer. I am wondering if the best course of action would be to create a new model which keeps a pointer to my base model. Every time the various data changed signals are emitted from the base model, my "proxy" model determines if a new sequence has been found. It then keeps track of all the various sequences in its own internal data structure which keeps QPersistenModelIndex indexes into the base model. Then my "proxy's" data() method would use these indexes to get the real data from the underlying model but parsed into the correct format.

Do this sound like a better approach?

In this case, I am also wondering how to display my data as a table where each row could have a different number of columns. Perhaps I could keep track of the row with the maximum number of columns and return this in columnCount()? Then my data() method would just return QVariant() for columns that don't exist in a given row.

@VRonin That's really useful, thank you very much. Also I didn't know about the "Model test", that's nice too.