diff options
Diffstat (limited to 'src/quick/doc/src/concepts/modelviewsdata/modelview.qdoc')
-rw-r--r-- | src/quick/doc/src/concepts/modelviewsdata/modelview.qdoc | 20 |
1 files changed, 20 insertions, 0 deletions
diff --git a/src/quick/doc/src/concepts/modelviewsdata/modelview.qdoc b/src/quick/doc/src/concepts/modelviewsdata/modelview.qdoc index 04dbf1cf20..555f730c9e 100644 --- a/src/quick/doc/src/concepts/modelviewsdata/modelview.qdoc +++ b/src/quick/doc/src/concepts/modelviewsdata/modelview.qdoc @@ -164,6 +164,16 @@ To visualize data, bind the view's \c model property to a model and the \snippet qml/qml-data-models/listmodel-listview.qml document + To get finer control over which roles are accessible, and to make delegates + more self-contained and usable outside of views, + \li{Required Properties}{required properties} can be used. If a delegate + contains required properties, the named roles are not provided. Instead, + the QML engine will check if the name of a required property matches that of + a model role. If so, that property will be bound to the corresponding value + from the model. + + \snippet qml/qml-data-models/listmodel-listview-required.qml document + If there is a naming clash between the model's properties and the delegate's properties, the roles can be accessed with the qualified \e model name instead. For example, if a \l Text type had \e type or \e age properties, @@ -186,6 +196,10 @@ To visualize data, bind the view's \c model property to a model and the 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. + \note \e model, \e index, and \e modelData roles are not accessible + if the delegate contains required properties, unless it has also required + properties with matching names. + QML provides several types of data models among the built-in set of QML types. In addition, models can be created with Qt C++ and then made available to \l{QQmlEngine} for use by @@ -417,6 +431,12 @@ ListView { \note The \c edit role is equal to \l Qt::EditRole. See \l{QAbstractItemModel::}{roleNames}() for the built-in role names. However, real life models would usually register custom roles. +\node If a model role is bound to a \li{Required Property}{required property}, assigning to +that property will not modify the model. It will instead break the binding to the model (just +like assigning to any other property breaks existing bindings). If you want to use +required properties and change the model data, make model also a required property and assign to +\e model.propertyName. + For more information, visit the \l{qtquick-modelviewsdata-cppmodels.html#changing-model-data}{Using C++ Models with Qt Quick Views} article. |