QIfPagingModel Class

Detailed Description

The QIfPagingModel should be used directly or as a base class whenever a lot of data needs to be presented in a ListView.

The model only fetches the data it really needs and can it can be configured how this can be done using the loadingType property.

The backend filling the model with data needs to implement the QIfPagingModelInterface class.

Setting it up

The QIfPagingModel is using QtInterfaceFramework's Dynamic Backend System and is derived from QIfAbstractFeatureListModel. Other than most "QtInterfaceFramework Feature classes", the QIfPagingModel doesn't automatically connect to available backends.

The easiest approach to set it up, is to connect to the same backend used by another feature. E.g. for connecting to the media backend, use the instance from the mediaplayer feature:

QIfMediaPlayer *player = new QIfMediaPlayer();
player->startAutoDiscovery();
QIfPagingModel *model = new QIfPagingModel();
model->setServiceObject(player->serviceObject());

Loading Types

Multiple loading types are supported, as the QIfPagingModel is made to work with asynchronous requests to fetch its data. The FetchMore loading type is the default and is using the canFetchMore()/fetchMore() functions of QAbstractItemModel to fetch new data once the view hits the end of the currently available data. As fetching can take some time, there is the fetchMoreThreshold property which controls how much in advance a new fetch should be started.

The other loading type is DataChanged. In contrast to FetchMore, the complete model is pre-populated with empty rows and the actual data for a specific row is fetched the first time the data() function is called. Once the data is available, the dataChanged() signal will be triggered for this row and the view will start to render the new data.

Please see the documentation of LoadingType for more details on how the modes work and when they are suitable to use.

See the Models section for more information about all models in QtInterfaceFramework.