QIviPagingModelInterface Class

The QIviPagingModelInterface defines the interface for backends to the QIviPagingModel feature class. More...

Header: #include <QIviPagingModelInterface>
qmake: QT += ivicore
Inherits: QIviFeatureInterface
Inherited By:

QIviSearchAndBrowseModelInterface

Public Functions

QIviPagingModelInterface(QObject *parent = ...)
virtual void fetchData(const QUuid &identifier, int start, int count) = 0
virtual void registerInstance(const QUuid &identifier) = 0
virtual void unregisterInstance(const QUuid &identifier) = 0

Signals

void countChanged(const QUuid &identifier = QUuid(), int count = -1)
void dataChanged(const QUuid &identifier, const QList<QVariant> &data, int start, int count)
void dataFetched(const QUuid &identifier, const QList<QVariant> &data, int start, bool moreAvailable)
void supportedCapabilitiesChanged(const QUuid &identifier, QtIviCoreModule::ModelCapabilities capabilities)

Detailed Description

The QIviPagingModelInterface is the interface used by QIviPagingModel

The interface is discovered by a QIviPagingModel object, which connects to it and sets it up.

Every QIviPagingModel generates its own QUuid which is passed to the backend interface and can be used to identify a model instance.

//TODO explain how the interface works on a example <example of a fully featured backend>

See also QIviPagingModel.

Member Function Documentation

QIviPagingModelInterface::QIviPagingModelInterface(QObject *parent = ...)

Constructs a backend interface.

The parent is sent to the QObject constructor.

[signal] void QIviPagingModelInterface::countChanged(const QUuid &identifier = QUuid(), int count = -1)

This signal is emitted when the current number of items in the QIviPagingModel instance identified by identifier changed. The new number of items is returned as count.

This signal is expected to be emitted after the model instance has requested new data for the first time by calling fetchData() and should be emitted before the data is returned by emitting the dataFetched() signal.

Note: If a null QQuuid is used as a identifier, all model instances will be informed.

See also fetchData() and dataFetched().

[signal] void QIviPagingModelInterface::dataChanged(const QUuid &identifier, const QList<QVariant> &data, int start, int count)

This signal is emitted whenever the data in the QIviPagingModel instance identified by identifier changed and the model needs to be updated. The new data is passed as data. The arguments start and count can be used to define the set of items which should be replaced with the new data.

For inserting a new item, the item is passed in data and start is used for where the item should be inserted, the count argument needs to be 0 as we don't want to replace existing data:

QList<ExampleItem> list;
ExampleItem item = ExampleItem();
list.insert(index, item);
QVariantList items = { QVariant::fromValue(item) };
emit dataChanged(items, index, 0);

Removing an item is very similar, start is used to indicate which item and count to indicate how much:

list.removeAt(index);
emit dataChanged(identifier, QVariantList(), index, 1);

Note: If a null QQuuid is used as a identifier, all model instances will be informed.

[signal] void QIviPagingModelInterface::dataFetched(const QUuid &identifier, const QList<QVariant> &data, int start, bool moreAvailable)

This signal is emitted as a result of a call to fetchData() and returns the requested data in the argument data to the QIviPagingModel instance identified by identifier. The arguments start holds the index where the data starts and moreAvailable holds whether there is more data available and a new fetchData() call can be used to retrieve this data.

Note: If a null QQuuid is used as a identifier, all model instances will be informed.

See also fetchData() and dataFetched().

[signal] void QIviPagingModelInterface::supportedCapabilitiesChanged(const QUuid &identifier, QtIviCoreModule::ModelCapabilities capabilities)

Emitted when the capabilities of the model instance identified by identifier changed.

Note: If a null QQuuid is used as a identifier, all model instances will be informed.

[pure virtual] void QIviPagingModelInterface::fetchData(const QUuid &identifier, int start, int count)

This function is called whenever new data needs to be retrieved by a QIviPagingModel identified by identifier.

The parameters start and count define the range of data which should be fetched. This method is expected to emit the dataFetched() signal once the new data is ready.

See also dataFetched().

[pure virtual] void QIviPagingModelInterface::registerInstance(const QUuid &identifier)

Registers the instance of QIviPagingModel identified by identifier with this backend. This function will be called by QIviPagingModel and all its derived classes after the initialize() function, but before any data will be requested e.g. via fetchData().

See also unregisterInstance.

[pure virtual] void QIviPagingModelInterface::unregisterInstance(const QUuid &identifier)

Unregisters the instance of QIviPagingModel identified by identifier with this backend. This function will be called by QIviPagingModel and all its derived classes before the ServiceObject gets disconnected and can be used to cleanup all cached data for this identifier.

See also registerInstance.

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