Qt Model-View update view?

Question

I have a model which is updated dynamically not related to the view. Which method should be called on the view to show the current models data?

Example:

StationListModel *model = new StationListModel(dynamic_list);
QListView *view = new QListView;
view->setModel(model);  //view set with empty model 
view->show();

In some point in time the dynamic_list is populated with new entries via a socket connection (nothing to do with View). How to populate the view with new data?

There is a `QAbstractItemView::update(const QModelIndex & index)`. `QAbstractItemView` is the base class of `QListView` — TheMeaningfulEngineer, Oct 31 '13 at 13:10

score 8 · Accepted Answer · answered Oct 31 '13 at 13:07

8

Model must emit signals to notify views when its data changed. Choose appropriate signals depending on how exactly data is changed:

dataChanged signal forces view to update specific cells, but not to create or remove cells.
layoutAboutToBeChanged and layoutChanged signals forces view to update everything.
signals about adding or removing rows and columns forces view to update accordingly.

answered Oct 31 '13 at 13:07

Pavel Strakhov

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What are the slots on the view that can catch them? – TheMeaningfulEngineer Oct 31 '13 at 13:09
1

It's internal view implementation. Views connect to the model's signals automatically. You don't need to think about it. – Pavel Strakhov Oct 31 '13 at 13:11
So after setting `view->setModel(model);` the view should update itself on every model change (assuming `dataChanged` or `layoutChanged` emmited) ? – TheMeaningfulEngineer Oct 31 '13 at 13:14
Yes, assuming that signals are emitted in correct order and with correct parameters. – Pavel Strakhov Oct 31 '13 at 13:17
4

@alan actually you shouldn't emit `layoutAboutToBeChanged` and friends directly but instead use the `beginInsert` and `endInsert` and family which will in turn emit the necessary signals – ratchet freak Oct 31 '13 at 14:07
4

@alan: *So after setting view->setModel(model); the view should update itself on every model change* That's the **whole point** of the model-view architecture. It'd be next to useless otherwise. – Kuba hasn't forgotten Monica Oct 31 '13 at 20:59
any subclass that overrides "`QListView::timerEvent(...)`" should call it manually to ensure `paintEvent` gets called (that did fix my case) – Top-Master Nov 17 '18 at 12:12

Qt Model-View update view?

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