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Data is provided to the delegate via named data roles which the delegate may bind to. The roles are exposed as properties of the \e model context property, though this property is set as a default property of the delegate so, unless there is a naming clash with a property in the delegate, the roles are usually accessed unqualified. The example below would have a clash between he \e color role of the model and the \e color property of the Rectangle. The clash is avoided by referencing the \e color property of the model by its full name: \e model.color. \code ListModel { id: myModel ListElement { color: "red" } ListElement { color: "green" } } Component { id: myDelegate Rectangle { width: 20; height: 20 color: model.color } } \endcode A special \e index role containing the index of the item in the model is also available. \e Note: the index role will be set to -1 if the item is removed from the model. If you bind to the index role, be sure that the logic accounts for the possibility of index being -1, i.e. that the item is no longer valid. Usually the item will shortly be destroyed, but it is possible to delay delegate destruction in some views via a delayRemove attached property. Models that do not have named roles will have the data provided via the \e modelData role. The \e modelData role is also provided for Models that have only one role. In this case the \e modelData role contains the same data as the named role. There are a number of QML elements that operate using data models: \list \o ListView \o GridView \o PathView \o \l Repeater \endlist QML supports several types of data model, which may be provided by QML or C++ (via QmlContext::setContextProperty(), for example). \section1 QML Data Models \section2 ListModel ListModel is a simple hierarchy of elements specified in QML. The available roles are specified by the \l ListElement properties. \code ListModel { id: fruitModel ListElement { name: "Apple" cost: 2.45 } ListElement { name: "Orange" cost: 3.25 } ListElement { name: "Banana" cost: 1.95 } } \endcode The above model has two roles, \e name and \e cost. These can be bound to by a ListView delegate, for example: \code Component { id: fruitDelegate Row { Text { text: "Fruit: " + name } Text { text: "Cost: $" + cost } } } ListView { model: fruitModel delegate: fruitDelegate } \endcode \section2 XmlListModel XmlListModel allows construction of a model from an XML data source. The roles are specified via the \l XmlRole element. The following model has three roles, \e title, \e link and \e description: \code XmlListModel { id: feedModel source: "http://rss.news.yahoo.com/rss/oceania" query: "/rss/channel/item" XmlRole { name: "title"; query: "title/string()" } XmlRole { name: "link"; query: "link/string()" } XmlRole { name: "description"; query: "description/string()" } } \endcode \section2 VisualItemModel VisualItemModel allows QML items to be provided as a model. This model contains both the data and delegate (its child items). This model does not provide any roles. \code VisualItemModel { id: itemModel Rectangle { height: 30; width: 80; color: "red" } Rectangle { height: 30; width: 80; color: "green" } Rectangle { height: 30; width: 80; color: "blue" } } ListView { anchors.fill: parent model: itemModel } \endcode Note that in the above example there is no delegate required. The items of the model itself provide the visual elements that will be positioned by the view. \section1 C++ Data Models \section2 QAbstractItemModel QAbstractItemModel provides the roles set via the QAbstractItemModel::setRoleNames() method. \section2 QStringList QStringList provides the contents of the list via the \e modelData role: \table \header \o \o \row \o \code // main.cpp QStringList dataList; dataList.append("Fred"); dataList.append("Ginger"); dataList.appenf("Skipper"); QmlContext *ctxt = view.rootContext(); ctxt->setContextProperty("myModel", QVariant::fromValue(&dataList)); \endcode \o \code // main.qml ListView { width: 100 height: 100 anchors.fill: parent model: myModel delegate: Component { Rectangle { height: 25 Text { text: modelData } } } } \endcode \endtable \note There is no way for the view to know that the contents of a QStringList have changed. If the QStringList is changed, it will be necessary to reset the model by calling QmlContext::setContextProperty() again. \section2 QList QList provides the properties of the objects in the list as roles. \code class DataObject : public QObject { Q_OBJECT Q_PROPERTY(QString name READ name WRITE setName) Q_PROPERTY(QString color READ color WRITE setColor) ... }; QList dataList; dataList.append(new DataObject("Item 1", "red")); dataList.append(new DataObject("Item 2", "green")); dataList.append(new DataObject("Item 3", "blue")); dataList.append(new DataObject("Item 4", "yellow")); QmlContext *ctxt = view.rootContext(); ctxt->setContextProperty("myModel", QVariant::fromValue(dataList)); \endcode The properties of the object may then be accessed in the delegate: \code ListView { width: 100 height: 100 anchors.fill: parent model: myModel delegate: Component { Rectangle { height: 25 width: 100 color: model.color Text { text: name } } } } \endcode Note: There is no way for the view to know that the contents of a QList have changed. If the QList is changed, it will be necessary to reset the model by calling QmlContext::setContextProperty() again. \section1 Other Data Models \section2 An Integer An Integer specifies a model containing the integer number of elements. There are no data roles. The following example creates a ListView with five elements: \code Component { id: itemDelegate Text { text: "I am item number: " + index } } ListView { model: 5 delegate: itemDelegate } \endcode \section2 An Object Instance An Object Instance specifies a model with a single Object element. The properties of the object are provided as roles. The example below creates a list with one item, showing the color of the \e myText text. Note the use of the fully qualified \e model.color property to avoid clashing with \e color property of the Text element in the delegate. \code Rectangle { Text { id: myText text: "Hello" color: "#dd44ee" } Component { id: myDelegate Text { text: model.color } } ListView { anchors.fill: parent anchors.topMargin: 30 model: myText delegate: myDelegate } } \endcode */