BindingBase.BindingGroupName Property

Definition

Namespace:

System.Windows.Data

Assembly:

PresentationFramework.dll

Gets or sets the name of the BindingGroup to which this binding belongs.

public:
 property System::String ^ BindingGroupName { System::String ^ get(); void set(System::String ^ value); };

public string BindingGroupName { get; set; }

member this.BindingGroupName : string with get, set

Public Property BindingGroupName As String

Property Value

String

The name of the BindingGroup to which this binding belongs.

Examples

The following examples are part of an application that checks whether the user has set the properties of two objects to equal values. The first example creates two TextBox controls, each of which is data bound to a different source: The binding of the first TextBox is part of the BindingGroup because the TextBox inherits the DataContext and BindingGroup from its parent StackPanel

The binding on the second TextBox is part of the BindingGroup because the Name of the BindingGroup and the BindingGroupName of the Binding are both set to bindingGroup.

<StackPanel Name="sp1"
            Margin="5"
            DataContext="{Binding Source={StaticResource object1}}"
            Validation.ValidationAdornerSite="{Binding ElementName=label1}"
            Orientation="Horizontal"
            HorizontalAlignment="Center">

  <StackPanel.BindingGroup>
    <BindingGroup Name="bindingGroup">
      <BindingGroup.ValidationRules>
        <src:BindingGroupValidationRule ValidatesOnTargetUpdated="True" />
      </BindingGroup.ValidationRules>
    </BindingGroup>
  </StackPanel.BindingGroup>

  <TextBlock Text="First string" />

  <TextBox Width="150"
           Text="{Binding Path=PropertyA}" />

  <TextBlock Text="Second string" />

  <TextBox Width="150"
           Text="{Binding Source={StaticResource object2}, 
    Path=PropertyB, BindingGroupName=bindingGroup, 
    TargetNullValue=please enter a string}" />

</StackPanel>

<Label Name="label1"
       Content="{Binding ElementName=sp1, Path=(Validation.Errors)[0].ErrorContent}"
       Margin="5"
       Foreground="Red"
       HorizontalAlignment="Center" />

The following example shows the ValidationRule that the previous example uses. In the Validate method, the example gets each source object from the BindingGroup and checks whether the properties of the objects are equal.

public class Type1
{
    public string PropertyA { get; set; }

    public Type1()
    {
        PropertyA = "Default Value";
    }
}

public class Type2
{
    public string PropertyB { get; set; }

    public Type2()
    {
    }
}

public class BindingGroupValidationRule : ValidationRule
{
    public override ValidationResult Validate(object value, System.Globalization.CultureInfo cultureInfo)
    {
        BindingGroup bg = value as BindingGroup;

        Type1 object1 = null;
        Type2 object2 = null;

        foreach (object item in bg.Items)
        {
            if (item is Type1)
            {
                object1 = item as Type1;
            }

            if (item is Type2)
            {
                object2 = item as Type2;
            }
        }

        if (object1 == null || object2 == null)
        {
            return new ValidationResult(false, "BindingGroup did not find source object.");
        }

        string string1 = bg.GetValue(object1, "PropertyA") as string;
        string string2 = bg.GetValue(object2, "PropertyB") as string;

        if (string1 != string2)
        {
            return new ValidationResult(false, "The two strings must be identical.");
        }

        return ValidationResult.ValidResult;
    }
}

Public Class Type1
    Public Property PropertyA() As String

    Public Sub New()
        PropertyA = "Default Value"
    End Sub
End Class

Public Class Type2
    Public Property PropertyB() As String

    Public Sub New()
    End Sub
End Class

Public Class BindingGroupValidationRule
    Inherits ValidationRule
    Public Overrides Function Validate(ByVal value As Object, ByVal cultureInfo As System.Globalization.CultureInfo) As ValidationResult
        Dim bg As BindingGroup = TryCast(value, BindingGroup)

        Dim object1 As Type1 = Nothing
        Dim object2 As Type2 = Nothing

        For Each item As Object In bg.Items
            If TypeOf item Is Type1 Then
                object1 = TryCast(item, Type1)
            End If

            If TypeOf item Is Type2 Then
                object2 = TryCast(item, Type2)
            End If
        Next item

        If object1 Is Nothing OrElse object2 Is Nothing Then
            Return New ValidationResult(False, "BindingGroup did not find source object.")
        End If

        Dim string1 As String = TryCast(bg.GetValue(object1, "PropertyA"), String)
        Dim string2 As String = TryCast(bg.GetValue(object2, "PropertyB"), String)

        If string1 <> string2 Then
            Return New ValidationResult(False, "The two strings must be identical.")
        End If

        Return ValidationResult.ValidResult

    End Function

End Class

Remarks

If BindingGroupName is not set, the binding belongs to a BindingGroup only if the binding's source and the DataContext of the parent element that has the BindingGroup are the same object.

If BindingGroupName is set to a value, the binding belongs to a BindingGroup if the following conditions are true:

• The Name of the BindingGroup and BindingGroupName are equal.

• The BindingGroup belongs to a parent element of the binding's target element.

If BindingGroupName is set to null, the binding is never a part of a BindingGroup.

You can include bindings that have a source that is different from the DataContext of the parent element that has the BindingGroup by setting Name of the BindingGroup and the BindingGroupName property of a binding to the same value. You can exclude bindings that have the same source as DataContext of the parent element that has the BindingGroup by setting Name of the BindingGroup and the BindingGroupName property of a binding to different values.