BindingGroup.Items Propiedad

Definición

Obtiene los orígenes que usan los objetos de enlace de BindingGroup.Gets the sources that are used by the Binding objects in the BindingGroup.

public:
 property System::Collections::IList ^ Items { System::Collections::IList ^ get(); };
public System.Collections.IList Items { get; }
member this.Items : System.Collections.IList
Public ReadOnly Property Items As IList

Valor de propiedad

Orígenes que usan los objetos de enlace de BindingGroup.The sources that are used by the Binding objects in the BindingGroup.

Ejemplos

Los ejemplos siguientes forman parte de una aplicación que comprueba si el usuario ha establecido las propiedades de dos objetos en los mismos valores.The following examples are part of an application that checks whether the user has set the properties of two objects to equal values. En el primer ejemplo se TextBox crean dos controles, cada uno de los cuales son datos enlazados a un origen diferente.The first example creates two TextBox controls, each of which are data bound to a different source. El enlace de la primera TextBox obtiene su origen, object1 TextBox , del DataContext elemento primario del control ( StackPanel).The binding of the first TextBox gets its source, object1, from the DataContext of the TextBox control's parent element (the StackPanel). En el segundo TextBox, el origen del enlace se establece en. object2On the second TextBox, the source of the binding is set to object2. En el ejemplo también se Label crea un que muestra los errores de validación.The example also creates a Label that displays validation errors.

<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" />

En el ejemplo siguiente se ValidationRule muestra el que utiliza el ejemplo anterior.The following example shows the ValidationRule that the previous example uses. En el BindingGroup método, el ejemplo obtiene cada objeto de origen de y comprueba si las propiedades de los objetos son iguales. ValidateIn 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

Comentarios

Cada objeto que se usa como origen se agrega a la Items propiedad una vez, incluso si el objeto se usa como el origen de varios enlaces.Each object that is used as a source is added into the Items property once, even if the object is used as the source for multiple bindings. A menudo, solo hay un elemento en Items, que es el objeto DataContext del elemento que utiliza BindingGroup.Often, there is just one item in Items, which is the object that is the DataContext of the element that uses the BindingGroup. Sin embargo, es posible BindingGroup que un tenga varios orígenes.It is possible for a BindingGroup to have multiple sources, however. Por ejemplo, si los objetos de enlace comparten BindingGroupName el mismo pero usan objetos de origen diferentes, cada objeto que se usa como origen Itemsestá en.For example, if Binding objects share the same BindingGroupName but use different source objects, each object that is used as a source is in Items.

También puede haber varios objetos en Items si la ruta de acceso de un enlace se resuelve en una propiedad anidada del origen.There can also be multiple objects in Items if the path of a Binding resolves to a nested property of the source. Por ejemplo TextBox , supongamos que el enlace de un control forma parte BindingGroup de DataContext y su Customer es un objeto, que tiene una propiedad Addressde tipo.For example, suppose a TextBox control's binding is a part of a BindingGroup and its DataContext is a Customer object, which has a property of type Address. Si el Path Address.ZipCode Items de Binding es la propiedad, seagregaAddress a la propiedad.If the Path of the Binding is the Address.ZipCode property, the Address is added to the Items property.

Se aplica a