Data-grid Contexts

At the heart of every grid and detail is a DataGridContext that provides contextual information on, and access to, the items they contain and acts as a hub through which all interactions with the grid or detail pass.

If the source of a context is a detail, the detail configuration that was applied to the detail, its parent data item, and the parent item's context can be retrieved through the context's SourceDetailConfiguration, ParentItem, and ParentDataGridContext properties, respectively; however, if the source of a context is a grid, these three properties will return null (Nothing in Visual Basic). In either case, the parent grid, or the grid that is the source of the context, can be retrieved through a context's DataGridControl property.

Some of the property values provided by each datagrid context correspond to the property values of the grid or the detail configuration that was applied to the detail that is the source of its associated context (see Table 1).

Property	Description
AllowDetailToggle	Gets a value indicating whether the end user can toggle the expansion state of details in the context.
AutoFilterValues	Gets a dictionary that contains a list of the context's DataGridItemProperty objects with their corresponding auto-filter values.
Columns	Gets a list of the columns contained in the context.
DefaultGroupConfiguration	Gets the default configuration that will be used by any groups in the context for which an explicit group configuration is not provided.
DetailConfigurations	Gets a list of the configurations that will be applied to their corresponding details.
DistinctValues	Gets a dictionary that contains a list of the context's DataGridItemProperty objects with their corresponding distinct values.
Footers	Gets a collection that contains the items that are located in the footer section of the context.
GroupConfigurationSelector	Gets a group-configuration selector that will be used to select the appropriate configuration for a group in the context based on its information and/or content.
GroupLevelDescriptions	Gets a collection of GroupLevelDescription objects that contain information on each group level contained in the context.
Headers	Gets a collection that contains the items that are located in the header section of the context.
ItemContainerStyle	Gets the style that is applied to the container element (DataRow) generated for each item in the context.
ItemContainerStyleSelector	Gets a style selector that selects the appropriate style to apply to each generated container element (DataRow) in the context.
VisibleColumns	Gets a list of the columns in the context whose Visible property is true, ordered according to their VisiblePosition.

In the case of the AutoFilterValues and DistinctValues properties, their values correspond to the value of the DistinctValues and AutoFilterValues properties of the DataGridCollectionView to which the source grid is bound or the AutoFilterValues property of the DetailDescription from which the source detail was created (the distinct values will be automatically created by the underlying DataGridCollectionView).

Each context exposes an Items property that represents the collection view that was used to generate the content of the context and whose type depends on the source of the context. If the source is a grid (DataGridControl), Items will be an ItemCollection; if the source is a detail, then Items will be a DataGridCollectionview.

Context Life Cycle

The data-grid context of a grid always exists; however, detail contexts are created and exist only when they are expanded and will be destroyed when a detail is collapsed. A data-grid context's HasDetails property can be queried to determine if it has details; however, it does not indicate whether the details are expanded and consequently have a context. To know if the details of a specific data item are expanded and therefore have a context, the AreDetailsExpanded method can be used.

The context of expanded details contained in a collapsed group exist.

The current context, whose CurrentItem and CurrentColumn properties correspond to the GlobalCurrentItem and GlobalCurrentColumn of its parent grid, can be retrieved through the parent grid's CurrentContext property or by checking a context's IsCurrent property. If items are selected in the current context, they can be retrieved through the context's SelectedItems collection and will also be part of the parent grid's GlobalSelectedItems collection. The contexts in which items are selected can be retrieved through the SelectedContexts property.

Retrieving a Context

In addition to the current and selected contexts, which can be retrieved through a grid's CurrentContext and SelectedContexts properties, the data-grid context of any container can also be retrieved using the DataGridControl.DataGridContext attached property. A context's child contexts can be retrieved through the GetChildContext method, which attempts to retrieve a child context based on the specified data item and detail configuration, and the GetChildContexts method, which retrieves all immediate child contexts.

Manipulating Context Items

The items that are contained in a context, be they groups, details, data items, or any items contained in the headers or footers of the grid or detail that is the source of the configuration, can be manipulated through their context.

A context's BeginEdit method will place the context's current item or a specific item, which must be part of the context, in edit mode. Modifications made to edited item will be committed when EndEdit is called or discarded when CancelEdit is called (see Editing Data topic).

The expansion state of all same-level child details can be modified through their context using its CollapseDetails, ExpandDetails, and ToggleDetailExpansion methods. Likewise, the CollapseGroup, ExpandGroup, and ToggleGroupExpansion methods can be used to modify the expansion state of a specific group while the IsGroupExpanded method can be used to determine if a particular group is expanded. Like the BeginEdit method, the specified data item or group must be part of the context or an exception will be thrown.

Examples

All examples in this topic assume that the grid is bound to the Employees table of the Northwind database, unless stated otherwise.

The following example demonstrates how to provide a default detail configuration that will be applied to all details in a grid and any descendant details for which an explicit detail configuration has not been provided.

XAML	Copy Code
<Grid> <Grid.Resources> <xcdg:DataGridCollectionViewSource x:Key="cvs_employees" Source="{Binding Source={x:Static Application.Current}, Path=Employees}" /> <xcdg:IndexToOddConverter x:Key="rowIndexConverter" /> <Style x:Key="alternatingDataRowStyle" TargetType="{x:Type xcdg:DataRow}"> <Style.Triggers> <DataTrigger Binding="{Binding RelativeSource={RelativeSource Self}, Path=(xcdg:DataGridVirtualizingPanel.ItemIndex), Converter={StaticResource rowIndexConverter}}" Value="True"> <Setter Property="Background" Value="AliceBlue" /> </DataTrigger> </Style.Triggers> </Style> </Grid.Resources> <xcdg:DataGridControl x:Name="EmployeesGrid" ItemsSource="{Binding Source={StaticResource cvs_employees}}" ItemsSourceName="Employee Information" AutoCreateDetailConfigurations="True"> <xcdg:DataGridControl.DefaultDetailConfiguration> <xcdg:DefaultDetailConfiguration UseDefaultHeadersFooters="False" ItemContainerStyle="{StaticResource alternatingDataRowStyle}" xcdg:TableView.ShowFixedColumnSplitter="False"> <xcdg:DefaultDetailConfiguration.DefaultGroupConfiguration> <xcdg:GroupConfiguration InitiallyExpanded="False" /> </xcdg:DefaultDetailConfiguration.DefaultGroupConfiguration> <xcdg:DefaultDetailConfiguration.Headers> <DataTemplate> <DockPanel> <xcdg:HierarchicalGroupLevelIndicatorPane xcdg:GroupLevelIndicatorPane.ShowIndicators="False" xcdg:TableView.CanScrollHorizontally="False" DockPanel.Dock="Left" /> <ContentPresenter Content="{Binding RelativeSource={RelativeSource Self}, Path=(xcdg:DataGridControl.DataGridContext).SourceDetailConfiguration.Title}" ContentTemplate="{Binding RelativeSource={RelativeSource Self}, Path=(xcdg:DataGridControl.DataGridContext).SourceDetailConfiguration.TitleTemplate}" /> </DockPanel> </DataTemplate> <DataTemplate> <xcdg:ColumnManagerRow AllowColumnReorder="False" AllowSort="False" /> </DataTemplate> </xcdg:DefaultDetailConfiguration.Headers> <xcdg:DefaultDetailConfiguration.Footers> <DataTemplate> <xcdg:InsertionRow Background="Cornsilk" /> </DataTemplate> </xcdg:DefaultDetailConfiguration.Footers> <xcdg:DefaultDetailConfiguration.DetailIndicatorStyle> <Style TargetType="{x:Type xcdg:DetailIndicator}"> <Setter Property="Background" Value="AliceBlue" /> </Style> </xcdg:DefaultDetailConfiguration.DetailIndicatorStyle> </xcdg:DefaultDetailConfiguration> </xcdg:DataGridControl.DefaultDetailConfiguration> </xcdg:DataGridControl> </Grid>

XAML

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<Grid>
  <Grid.Resources>
     <xcdg:DataGridCollectionViewSource x:Key="cvs_employees"
                                        Source="{Binding Source={x:Static Application.Current}, Path=Employees}" />
  
     <xcdg:IndexToOddConverter x:Key="rowIndexConverter" />
  
     <Style x:Key="alternatingDataRowStyle"
            TargetType="{x:Type xcdg:DataRow}">
        <Style.Triggers>
           <DataTrigger Binding="{Binding RelativeSource={RelativeSource Self},
                             Path=(xcdg:DataGridVirtualizingPanel.ItemIndex),
                             Converter={StaticResource rowIndexConverter}}"
                        Value="True">
              <Setter Property="Background"
                      Value="AliceBlue" />
           </DataTrigger>
        </Style.Triggers>
     </Style>
 
  </Grid.Resources>
  <xcdg:DataGridControl x:Name="EmployeesGrid"
                      ItemsSource="{Binding Source={StaticResource cvs_employees}}"
                      ItemsSourceName="Employee Information"
                      AutoCreateDetailConfigurations="True">
    <xcdg:DataGridControl.DefaultDetailConfiguration>
       <xcdg:DefaultDetailConfiguration UseDefaultHeadersFooters="False"
                                        ItemContainerStyle="{StaticResource alternatingDataRowStyle}"
                                        xcdg:TableView.ShowFixedColumnSplitter="False">
          <xcdg:DefaultDetailConfiguration.DefaultGroupConfiguration>
             <xcdg:GroupConfiguration InitiallyExpanded="False" />
          </xcdg:DefaultDetailConfiguration.DefaultGroupConfiguration>
          <xcdg:DefaultDetailConfiguration.Headers>
             <DataTemplate>
                <DockPanel>
                   <xcdg:HierarchicalGroupLevelIndicatorPane  xcdg:GroupLevelIndicatorPane.ShowIndicators="False"
                                                              xcdg:TableView.CanScrollHorizontally="False"
                                                              DockPanel.Dock="Left" />
                   <ContentPresenter Content="{Binding RelativeSource={RelativeSource Self},
                                     Path=(xcdg:DataGridControl.DataGridContext).SourceDetailConfiguration.Title}"
                             ContentTemplate="{Binding RelativeSource={RelativeSource Self},
                             Path=(xcdg:DataGridControl.DataGridContext).SourceDetailConfiguration.TitleTemplate}" />
                </DockPanel>
             </DataTemplate>
             <DataTemplate>
                <xcdg:ColumnManagerRow AllowColumnReorder="False"
                                       AllowSort="False" />
             </DataTemplate>
          </xcdg:DefaultDetailConfiguration.Headers>
          <xcdg:DefaultDetailConfiguration.Footers>
             <DataTemplate>
                <xcdg:InsertionRow Background="Cornsilk" />
             </DataTemplate>
          </xcdg:DefaultDetailConfiguration.Footers>
          <xcdg:DefaultDetailConfiguration.DetailIndicatorStyle>
             <Style TargetType="{x:Type xcdg:DetailIndicator}">
                <Setter Property="Background"
                        Value="AliceBlue" />
             </Style>
          </xcdg:DefaultDetailConfiguration.DetailIndicatorStyle>
       </xcdg:DefaultDetailConfiguration>
    </xcdg:DataGridControl.DefaultDetailConfiguration>
 </xcdg:DataGridControl>
</Grid>

The following example demonstrates how to retrieve the child contexts of the master data items and collapse any expanded details using the CollapseDetail method.

XAML	Copy Code
<Grid> <Grid.Resources> <xcdg:DataGridCollectionViewSource x:Key="cvs_employees" Source="{Binding Source={x:Static Application.Current}, Path=Employees}"/> </Grid.Resources> <DockPanel> <Button Content="Collapse All Details" Click="Button_Click" DockPanel.Dock="Top"/> <xcdg:DataGridControl x:Name="EmployeesGrid" ItemsSource="{Binding Source={StaticResource cvs_employees}}" ItemsSourceName="Order Information" AutoCreateDetailConfigurations="True"/> </DockPanel> </Grid>

XAML

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<Grid>
  <Grid.Resources>
     <xcdg:DataGridCollectionViewSource x:Key="cvs_employees"
                                        Source="{Binding Source={x:Static Application.Current},
                                                         Path=Employees}"/>
 
  </Grid.Resources>
 
  <DockPanel>
     <Button Content="Collapse All Details"
             Click="Button_Click"
             DockPanel.Dock="Top"/>
     <xcdg:DataGridControl x:Name="EmployeesGrid"
                           ItemsSource="{Binding Source={StaticResource cvs_employees}}"
                           ItemsSourceName="Order Information"
                           AutoCreateDetailConfigurations="True"/>
  </DockPanel>
</Grid>

The next example provides the implementation of the button's Click event.

VB.NET	Copy Code
Private Sub Button_Click( ByVal sender As Object, ByVal e As RoutedEventArgs ) Dim childContexts As New List( Of DataGridContext)( Me.EmployeesGrid.GetChildContexts() ) Dim context As DataGridContext For Each context In childContexts context.ParentDataGridContext.CollapseDetails( context.ParentItem ) Next context End Sub

VB.NET

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Private Sub Button_Click( ByVal sender As Object, ByVal e As RoutedEventArgs )
  Dim childContexts As New List( Of DataGridContext)( Me.EmployeesGrid.GetChildContexts() )
  Dim context As DataGridContext
  For Each context In childContexts
    context.ParentDataGridContext.CollapseDetails( context.ParentItem )
  Next context
End Sub

C#	Copy Code
private void Button_Click( object sender, RoutedEventArgs e ) { List<DataGridContext> childContexts = new List<DataGridContext>( this.EmployeesGrid.GetChildContexts() ); foreach( DataGridContext context in childContexts ) { context.ParentDataGridContext.CollapseDetails( context.ParentItem ); } }

Copy Code

private void Button_Click( object sender, RoutedEventArgs e )
{
 List<DataGridContext> childContexts = new List<DataGridContext>( this.EmployeesGrid.GetChildContexts() );
 foreach( DataGridContext context in childContexts )
 {
   context.ParentDataGridContext.CollapseDetails( context.ParentItem );
 }     
}