VisualDataModel

The delegate provides a template defining each item instantiated by a view. The index is exposed as an accessible index property. Properties of the model are also available depending upon the type of Data Model.

This property holds the name of the group used to filter the visual data model.

Only items which belong to this group are visible to a view.

By default this is the items group.

This property holds a visual data model's group definitions.

Groups define a sub-set of the items in a visual data model and can be used to filter a model.

For every group defined in a VisualDataModel two attached properties are added to each delegate item. The first of the form VisualDataModel.inGroupName holds whether the item belongs to the group and the second VisualDataModel.groupNameIndex holds the index of the item in that group.

The following example illustrates using groups to select items in a model.

 import QtQuick 2.0

 Rectangle {
     width: 200; height: 100

     VisualDataModel {
         id: visualModel
         model: ListModel {
             ListElement { name: "Apple" }
             ListElement { name: "Orange" }
         }

         groups: [
             VisualDataGroup { name: "selected" }
         ]

         delegate: Rectangle {
             id: item
             height: 25
             width: 200
             Text {
                 text: {
                     var text = "Name: " + name
                     if (item.VisualDataModel.inSelected)
                         text += " (" + item.VisualDataModel.selectedIndex + ")"
                     return text;
                 }
             }
             MouseArea {
                 anchors.fill: parent
                 onClicked: item.VisualDataModel.inSelected = !item.VisualDataModel.inSelected
             }
         }
     }

     ListView {
         anchors.fill: parent
         model: visualModel
     }
 }

This property holds visual data model's default group to which all new items are added.

This property holds the model providing data for the VisualDataModel.

The model provides a set of data that is used to create the items for a view. For large or dynamic datasets the model is usually provided by a C++ model object. The C++ model object must be a QAbstractItemModel subclass or a simple list.

Models can also be created directly in QML, using a ListModel or XmlListModel.

See also Data Models.

The parts property selects a VisualDataModel which creates delegates from the part named. This is used in conjunction with the Package element.

For example, the code below selects a model which creates delegates named list from a Package:

 VisualDataModel {
     id: visualModel
     delegate: Package {
         Item { Package.name: "list" }
     }
     model: myModel
 }

 ListView {
     width: 200; height:200
     model: visualModel.parts.list
 }

See also Package.

This property holds visual data model's persisted items group.

Items in this group are not destroyed when released by a view, instead they are persisted until removed from the group.

An item can be removed from the persistedItems group by setting the VisualDataModel.inPersistedItems property to false. If the item is not referenced by a view at that time it will be destroyed. Adding an item to this group will not create a new instance.

Items returned by the QtQuick2::VisualDataGroup::create() function are automatically added to this group.

QAbstractItemModel provides a hierarchical tree of data, whereas QML only operates on list data. rootIndex allows the children of any node in a QAbstractItemModel to be provided by this model.

This property only affects models of type QAbstractItemModel that are hierarchical (e.g, a tree model).

For example, here is a simple interactive file system browser. When a directory name is clicked, the view's rootIndex is set to the QModelIndex node of the clicked directory, thus updating the view to show the new directory's contents.

main.cpp:

 int main(int argc, char ** argv)
 {
     QApplication app(argc, argv);

     QQuickView view;

     QDirModel model;
     view.rootContext()->setContextProperty("dirModel", &model);

     view.setSource(QUrl::fromLocalFile("view.qml"));
     view.show();

     return app.exec();
 }

view.qml:

 import QtQuick 2.0

 ListView {
     id: view
     width: 300
     height: 400

     model: VisualDataModel {
         model: dirModel

         delegate: Rectangle {
             width: 200; height: 25
             Text { text: filePath }

             MouseArea {
                 anchors.fill: parent
                 onClicked: {
                     if (model.hasModelChildren)
                         view.model.rootIndex = view.model.modelIndex(index)
                 }
             }
         }
     }
 }

If the model is a QAbstractItemModel subclass, the delegate can also reference a hasModelChildren property (optionally qualified by a model. prefix) that indicates whether the delegate's model item has any child nodes.

See also modelIndex() and parentModelIndex().

This attached property holds whether the item belongs to the default items VisualDataGroup.

Changing this property will add or remove the item from the items group.

It is attached to each instance of the delegate.

This attached property holds whether the item belongs to the persistedItems VisualDataGroup.

Changing this property will add or remove the item from the items group. Change with caution as removing an item from the persistedItems group will destroy the current instance if it is not referenced by a model.

It is attached to each instance of the delegate.

This attached property holds the index of the item in the default items VisualDataGroup.

It is attached to each instance of the delegate.

This attached property holds the index of the item in the persistedItems VisualDataGroup.

It is attached to each instance of the delegate.

QAbstractItemModel provides a hierarchical tree of data, whereas QML only operates on list data. This function assists in using tree models in QML.

Returns a QModelIndex for the specified index. This value can be assigned to rootIndex.

See also rootIndex.

QAbstractItemModel provides a hierarchical tree of data, whereas QML only operates on list data. This function assists in using tree models in QML.

Returns a QModelIndex for the parent of the current rootIndex. This value can be assigned to rootIndex.

See also rootIndex.