/*! 
\page qmlmodels.html
\target qmlmodels
\title Data Models

Some QML Items use Data Models to provide the data to be displayed.
These items typically require a \e delegate component that
creates an instance for each item in the model.  Models may be static, or
have items modified, inserted, removed or moved dynamically.

Data is provided to the delegate via named data roles which the
delegate may bind to.  A special \e index role containing the
index of the item in the model is also available.  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 {qml-repeater}{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

\list
\o ListModel is a simple hierarchy of elements specified in QML.  The
available roles are specified by the \l ListElement properties.
\o XmlListModel allows construction of a model from an XML data source. The roles
are specified via the \l XmlRole element.
\o 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.
\endlist


\section1 C++ Data Models

\list
\o QAbstractItemModel provides the roles set via the QAbstractItemModel::setRoleNames() method.
\o QStringList provides the contents of the list via the \e modelData role.
\o QList<QObject*> provides the properties of the objects in the list as roles.
\endlist


\section1 Other Data Models

\list
\o An Integer specifies a model containing the integer number of elements.
There are no data roles.
\o An Object Instance specifies a model with a single Object element.  The
properties of the object are provided as roles.
\endlist

*/