ValueFactoryExtension Class

Allows you to create unshared instances of objects in styles. The extension creates these instances for each element that uses the style.

Namespace: DevExpress.Mvvm.UI

Assembly: DevExpress.Xpf.Core.v23.2.dll

NuGet Package: DevExpress.Wpf.Core

Declaration

C#

public class ValueFactoryExtension :
    MarkupExtension

VB.NET

Public Class ValueFactoryExtension
    Inherits MarkupExtension

Remarks

Code samples in this topic contain two GridControls. Their View property is defined in the gridStyle resource.

If you create a TreeListView instance in a style without the ValueFactoryExtension, WPF does the following:

1. Creates the TreeListView instance for the first GridControl.
2. Creates the TreeListView instance for the second GridControl and deletes the instance created for the first GridControl.
3. The first GridControl‘s View property is null. As a result, the GridControl displays its default view (TableView).

XAML

<Window.Resources>
    <Style TargetType="dxg:GridControl" x:Key="gridStyle">
        <Setter Property="ItemsSource" Value="{Binding Persons}"/>
        <Setter Property="AutoGenerateColumns" Value="AddNew"/>
        <Setter Property="EnableSmartColumnsGeneration" Value="True"/>
        <Setter Property="View">
            <Setter.Value>
                <dxg:TreeListView KeyFieldName="ID" ParentFieldName="ParentID" 
                                  AutoWidth="True" AutoExpandAllNodes="True"/>
            </Setter.Value>
        </Setter>
    </Style>
</Window.Resources>
<Grid>
    <Grid.RowDefinitions>
        <RowDefinition/>
        <RowDefinition/>
    </Grid.RowDefinitions>
    <dxg:GridControl Style="{StaticResource gridStyle}"/>
    <dxg:GridControl Style="{StaticResource gridStyle}" Grid.Row="1"/>
</Grid>

The ValueFactoryExtension creates object instances for all elements that use the style:

XAML

<Window.Resources>
    <Style TargetType="dxg:GridControl" x:Key="gridStyle">
        <Setter Property="ItemsSource" Value="{Binding Persons}"/>
        <Setter Property="AutoGenerateColumns" Value="AddNew"/>
        <Setter Property="EnableSmartColumnsGeneration" Value="True"/>
        <Setter Property="View">
            <Setter.Value>
                <dxmvvm:ValueFactory>
                    <DataTemplate>
                        <dxg:TreeListView KeyFieldName="ID" ParentFieldName="ParentID" 
                                          AutoWidth="True" AutoExpandAllNodes="True"/>
                    </DataTemplate>
                </dxmvvm:ValueFactory>
            </Setter.Value>
        </Setter>
    </Style>
</Window.Resources>
<Grid>
    <Grid.RowDefinitions>
        <RowDefinition/>
        <RowDefinition/>
    </Grid.RowDefinitions>
    <dxg:GridControl Style="{StaticResource gridStyle}"/>
    <dxg:GridControl Style="{StaticResource gridStyle}" Grid.Row="1"/>
</Grid>

Inheritance

Object

MarkupExtension

ValueFactoryExtension