How to inform listview that model data has changed?

philk

Whats the recommended way to notify the listview that an item in its model has changed?
I would like to not use the layoutChanged() signal, as it seems to be to verbose. I already know which item has changed, and want to signal only this particular item.

SGaist

Hi,

You can use "dataChanged":http://qt-project.org/doc/qt-4.8/qabstractitemmodel.html#dataChanged with both first and last item pointing to the same index.

Hope it helps

philk

Thanks, and how would my model item know about the model its contained in to inform it?

SGaist

I am not sure I am following you correctly:

You do have a custom model right ?
The where does your changes come from ?

philk

Lets say the changes come from a file system change listener. The display text of the model item should change, when its underlying file changes.

SGaist

If your model is custom, the listener should notify your model that something has changed, then you should update the model content and emit the signal

philk

Let me explain using some pseudo code:
@
class ModelItem {
ModelItem(file) {
registerChangeHandler(file, this, &ModelItem::fileChanged)
}

void fileChanged(file) {
// How do I update the model, this ModelItem is part of?
}
}

class Model : public QAbstractItemModel {
}
@
In fileChanged() how do I update my model, which will then in turn update the UI?

SGaist

Are you sure that fileChanged should be in the item and not the model ?

philk

Yes, because other items of the Model are not backed by a File, and don't need change listeners. Every item knows better how it should update itself. The Model is just a collection of different items.