ItemsControl.ItemBindingGroup Property

Definition

Namespace:

System.Windows.Controls

Assembly:

PresentationFramework.dll

Gets or sets the BindingGroup that is copied to each item in the ItemsControl.

public:
 property System::Windows::Data::BindingGroup ^ ItemBindingGroup { System::Windows::Data::BindingGroup ^ get(); void set(System::Windows::Data::BindingGroup ^ value); };

[System.ComponentModel.Bindable(true)]
public System.Windows.Data.BindingGroup ItemBindingGroup { get; set; }

[<System.ComponentModel.Bindable(true)>]
member this.ItemBindingGroup : System.Windows.Data.BindingGroup with get, set

Public Property ItemBindingGroup As BindingGroup

Property Value

BindingGroup

The BindingGroup that is copied to each item in the ItemsControl.

Attributes

BindableAttribute

Examples

The following example is part of an application that prompts the user to enter multiple customers and assign a sales representative to each customer, and then checks that the sales representative and the customer belong to the same region. The example sets the ItemBindingGroup of the ItemsControl so the ValidationRule, AreasMatch, will validate each item. The example also creates a Label that displays validation errors. Notice that the Content of the Label is bound to a ValidationError that it gets from the Validation.ValidationAdornerSiteForProperty property. The value of Validation.ValidationAdornerSiteForProperty is the item container that has the error.

<ItemsControl Name="customerList"  ItemTemplate="{StaticResource ItemTemplate}"
              ItemsSource="{Binding}">
  <ItemsControl.ItemBindingGroup>
    <BindingGroup>
      <BindingGroup.ValidationRules>
        <src:AreasMatch/>
      </BindingGroup.ValidationRules>
    </BindingGroup>
  </ItemsControl.ItemBindingGroup>
  <ItemsControl.ItemContainerStyle>
    <Style TargetType="{x:Type ContentPresenter}">
      <Setter Property="Validation.ValidationAdornerSite"
              Value="{Binding ElementName=validationErrorReport}"/>
    </Style>
  </ItemsControl.ItemContainerStyle>
</ItemsControl>

<Label Name="validationErrorReport" 
       Content="{Binding RelativeSource={RelativeSource Self}, 
       Path=(Validation.ValidationAdornerSiteFor).(Validation.Errors)[0].ErrorContent}"
       Margin="5" Foreground="Red" HorizontalAlignment="Center"/>

The following example gets the item container and calls UpdateSources on the container's BindingGroup to validate the data. You must validate the data by calling a method on the item container's BindingGroup, not on the ItemBindingGroup of the ItemsControl.

void saveCustomer_Click(object sender, RoutedEventArgs e)
{
    Button btn = sender as Button;
    FrameworkElement container = (FrameworkElement) customerList.ContainerFromElement(btn);

    // If the user is trying to change an items, when another item has an error,
    // display a message and cancel the currently edited item.
    if (bindingGroupInError != null && bindingGroupInError != container.BindingGroup)
    {
        MessageBox.Show("Please correct the data in error before changing another customer");
        container.BindingGroup.CancelEdit();
        return;
    }

    if (container.BindingGroup.UpdateSources())
    {
        bindingGroupInError = null;
        MessageBox.Show("Item Saved");
    }
    else
    {
        bindingGroupInError = container.BindingGroup;
    }
}

Private Sub saveCustomer_Click(ByVal sender As Object, ByVal e As RoutedEventArgs)
    Dim btn As Button = TryCast(sender, Button)
    Dim container As FrameworkElement = CType(customerList.ContainerFromElement(btn), FrameworkElement)

    ' If the user is trying to change an items, when another item has an error,
    ' display a message and cancel the currently edited item.
    If bindingGroupInError IsNot Nothing AndAlso bindingGroupInError IsNot container.BindingGroup Then
        MessageBox.Show("Please correct the data in error before changing another customer")
        container.BindingGroup.CancelEdit()
        Return
    End If

    If container.BindingGroup.UpdateSources() Then
        bindingGroupInError = Nothing
        MessageBox.Show("Item Saved")
    Else
        bindingGroupInError = container.BindingGroup
    End If

End Sub

Remarks

When you set the ItemBindingGroup property, each item container gets a BindingGroup that has the same ValidationRule objects as the ItemBindingGroup, but the properties that describe the data in the bindings, such as Items and BindingExpressions, are specific to the data for each item in the ItemsControl. You must access the item container's BindingGroup to perform operations such as validate the data and check for errors on an item.