EntityChangedParams Clase

Definición

Espacio de nombres:

System.Data.Services.Client

Ensamblado:

System.Data.Services.Client.dll

Encapsula los argumentos de un delegado PropertyChanged.

public ref class EntityChangedParams sealed

public sealed class EntityChangedParams

type EntityChangedParams = class

Public NotInheritable Class EntityChangedParams

Herencia

Object

EntityChangedParams

Ejemplos

La siguiente página de código subyacente para el archivo XAML crea un DataServiceCollection<T> con métodos personalizados a los que se llama cuando se producen cambios en los datos enlazados a la colección de enlaces. Cuando se produce el evento CollectionChanged, el método proporcionado evita que se elimine del servicio de datos un elemento que se ha quitado de la colección de enlaces. Cuando se produce el evento PropertyChanged, se valida el valor de ShipDate para asegurarse de que no se realizan cambios en los pedidos que ya han enviado.

using System;
using System.Collections.Specialized;
using System.Data.Services.Client;
using System.Linq;
using System.Windows;
using NorthwindClient.Northwind;

namespace NorthwindClient
{
    public partial class CustomerOrdersCustom : Window
    {
        private NorthwindEntities context;
        private DataServiceCollection<Customer> trackedCustomers;
        private const string customerCountry = "Germany";
        private const string svcUri = "http://localhost:12345/Northwind.svc/";

        public CustomerOrdersCustom()
        {
            //InitializeComponent();
        }

        private void Window_Loaded(object sender, RoutedEventArgs e)
        {
            try
            {
                // Initialize the context for the data service.
                context = new NorthwindEntities(new Uri(svcUri));

                // Create a LINQ query that returns customers with related orders.
                var customerQuery = from cust in context.Customers.Expand("Orders")
                                    where cust.Country == customerCountry
                                    select cust;

                // Create a new collection for binding based on the LINQ query.
                trackedCustomers = new DataServiceCollection<Customer>(customerQuery,
                    TrackingMode.AutoChangeTracking,"Customers",
                    OnPropertyChanged, OnCollectionChanged);

                // Bind the root StackPanel element to the collection;
                // related object binding paths are defined in the XAML.
                LayoutRoot.DataContext = trackedCustomers;
            }
            catch (DataServiceQueryException ex)
            {
                MessageBox.Show("The query could not be completed:\n" + ex.ToString());
            }
            catch (InvalidOperationException ex)
            {
                MessageBox.Show("The following error occurred:\n" + ex.ToString());
            }
        }

        // Method that is called when the CollectionChanged event is handled.
        private bool OnCollectionChanged(
            EntityCollectionChangedParams entityCollectionChangedinfo)
        {
            if (entityCollectionChangedinfo.Action ==
                NotifyCollectionChangedAction.Remove)
            {
                // Delete the related items when an order is deleted.
                if (entityCollectionChangedinfo.TargetEntity.GetType() == typeof(Order))
                {
                    // Get the context and object from the supplied parameter.
                    DataServiceContext context = entityCollectionChangedinfo.Context;
                    Order deletedOrder = entityCollectionChangedinfo.TargetEntity as Order;

                    if (deletedOrder.Order_Details.Count == 0)
                    {
                        // Load the related OrderDetails.
                        context.LoadProperty(deletedOrder, "Order_Details");
                    }

                    // Delete the order and its related items;
                    foreach (Order_Detail item in deletedOrder.Order_Details)
                    {
                        context.DeleteObject(item);
                    }

                    // Delete the order and then return true since the object is already deleted.
                    context.DeleteObject(deletedOrder);

                    return true;
                }
                else
                {
                    return false;
                }
            }
            else
            {
                // Use the default behavior.
                return false;
            }
        }

        // Method that is called when the PropertyChanged event is handled.
        private bool OnPropertyChanged(EntityChangedParams entityChangedInfo)
        {
            // Validate a changed order to ensure that changes are not made
            // after the order ships.
            if ((entityChangedInfo.Entity.GetType() == typeof(Order)) &&
                ((Order)(entityChangedInfo.Entity)).ShippedDate < DateTime.Today)
            {
                throw new ApplicationException(string.Format(
                    "The order {0} cannot be changed because it shipped on {1}.",
                    ((Order)(entityChangedInfo.Entity)).OrderID,
                    ((Order)(entityChangedInfo.Entity)).ShippedDate));
            }
            return false;
        }

        private void deleteButton_Click(object sender, RoutedEventArgs e)
        {
            if (customerIDComboBox.SelectedItem != null)
            {
                // Get the Orders binding collection.
                DataServiceCollection<Order> trackedOrders =
                    ((Customer)(customerIDComboBox.SelectedItem)).Orders;

                // Remove the currently selected order.
                trackedOrders.Remove((Order)(ordersDataGrid.SelectedItem));
            }
        }

        private void saveChangesButton_Click(object sender, RoutedEventArgs e)
        {
            try
            {
                // Save changes to the data service.
                context.SaveChanges();
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.ToString());
            }
        }
    }
}

Imports System.Collections.Generic
Imports System.Linq
Imports System.Text
Imports System.Windows
Imports System.Windows.Controls
Imports System.Windows.Data
Imports System.Windows.Documents
Imports System.Windows.Input
Imports System.Windows.Media
Imports System.Windows.Media.Imaging
Imports System.Windows.Navigation
Imports System.Windows.Shapes
Imports System.Data.Services.Client
Imports NorthwindClient.Northwind
Imports System.Collections.Specialized

Partial Public Class CustomerOrdersCustom
    Inherits Window
    Private context As NorthwindEntities
    Private trackedCustomers As DataServiceCollection(Of Customer)
    Private Const customerCountry As String = "Germany"
    Private Const svcUri As String = "http://localhost:12345/Northwind.svc/"
    Private Sub Window_Loaded(ByVal sender As Object, ByVal e As RoutedEventArgs)
        Try
            ' Initialize the context for the data service.
            context = New NorthwindEntities(New Uri(svcUri))

            ' Create a LINQ query that returns customers with related orders.
            Dim customerQuery = From cust In context.Customers.Expand("Orders") _
                                    Where cust.Country = customerCountry _
                                    Select cust

            ' Create a new collection for binding based on the LINQ query.
            trackedCustomers = New DataServiceCollection(Of Customer)(customerQuery, _
                    TrackingMode.AutoChangeTracking, "Customers", _
                    AddressOf OnMyPropertyChanged, AddressOf OnMyCollectionChanged)

            ' Bind the root StackPanel element to the collection
            ' related object binding paths are defined in the XAML.
            Me.LayoutRoot.DataContext = trackedCustomers
        Catch ex As DataServiceQueryException
            MessageBox.Show("The query could not be completed:\n" + ex.ToString())
        Catch ex As InvalidOperationException
            MessageBox.Show("The following error occurred:\n" + ex.ToString())
        End Try
    End Sub
    ' Method that is called when the CollectionChanged event is handled.
    Private Function OnMyCollectionChanged( _
        ByVal entityCollectionChangedinfo As EntityCollectionChangedParams) As Boolean
        If entityCollectionChangedinfo.Action = _
            NotifyCollectionChangedAction.Remove Then

            ' Delete the related items when an order is deleted.
            If entityCollectionChangedinfo.TargetEntity.GetType() Is GetType(Order) Then

                ' Get the context and object from the supplied parameter.
                Dim context = entityCollectionChangedinfo.Context
                Dim deletedOrder As Order = _
                CType(entityCollectionChangedinfo.TargetEntity, Order)

                If deletedOrder.Order_Details.Count = 0 Then
                    ' Load the related OrderDetails.
                    context.LoadProperty(deletedOrder, "Order_Details")
                End If

                ' Delete the order and its related items
                For Each item As Order_Detail In deletedOrder.Order_Details
                    context.DeleteObject(item)
                Next

                ' Delete the order and then return false since the object is already deleted.
                context.DeleteObject(deletedOrder)

                Return True
            Else
                Return False
            End If
        Else
            ' Use the default behavior.
            Return False
        End If
    End Function
    ' Method that is called when the PropertyChanged event is handled.
    Private Function OnMyPropertyChanged( _
    ByVal entityChangedInfo As EntityChangedParams) As Boolean
        ' Validate a changed order to ensure that changes are not made 
        ' after the order ships.
        If entityChangedInfo.Entity.GetType() Is GetType(Order) AndAlso _
            (CType(entityChangedInfo.Entity, Order).ShippedDate < DateTime.Today) Then
            Throw New ApplicationException(String.Format( _
                "The order {0} cannot be changed because it shipped on {1}.", _
                CType(entityChangedInfo.Entity, Order).OrderID, _
                CType(entityChangedInfo.Entity, Order).ShippedDate))
            Return False
        Else
            Return True
        End If
    End Function
    Private Sub deleteButton_Click(ByVal sender As Object, ByVal e As RoutedEventArgs)
        ' Get the Orders binding collection.
        If customerIDComboBox.SelectedItem IsNot Nothing Then
            Dim trackedOrders As DataServiceCollection(Of Order) = _
                (CType(customerIDComboBox.SelectedItem, Customer)).Orders

            ' Remove the currently selected order.
            trackedOrders.Remove(CType(ordersDataGrid.SelectedItem, Order))
        End If
    End Sub
    Private Sub saveChangesButton_Click(ByVal sender As Object, ByVal e As RoutedEventArgs)
        Try
            ' Save changes to the data service.
            context.SaveChanges()
        Catch ex As Exception
            MessageBox.Show(ex.ToString())
        End Try
    End Sub
End Class

Imports System.Collections.Generic
Imports System.Linq
Imports System.Text
Imports System.Windows
Imports System.Windows.Controls
Imports System.Windows.Data
Imports System.Windows.Documents
Imports System.Windows.Input
Imports System.Windows.Media
Imports System.Windows.Media.Imaging
Imports System.Windows.Navigation
Imports System.Windows.Shapes
Imports System.Data.Services.Client
Imports NorthwindClient.NorthwindModel
Imports System.Collections.Specialized

Partial Public Class CustomerOrdersCustom
    Inherits Window
    Private context As NorthwindEntities
    Private trackedCustomers As DataServiceCollection(Of Customers)
    Private Const customerCountry As String = "Germany"
    Private Const svcUri As String = "http://localhost:12345/Northwind.svc/"
    Private Sub Window_Loaded(ByVal sender As Object, ByVal e As RoutedEventArgs)
        Try
            ' Initialize the context for the data service.
            context = New NorthwindEntities(New Uri(svcUri))

            ' Create a LINQ query that returns customers with related orders.
            Dim customerQuery = From cust In context.Customers.Expand("Orders") _
                                    Where cust.Country = customerCountry _
                                    Select cust

            ' Create a new collection for binding based on the LINQ query.
            trackedCustomers = New DataServiceCollection(Of Customers)(customerQuery, _
                    TrackingMode.AutoChangeTracking, "Customers", _
                    AddressOf OnMyPropertyChanged, AddressOf OnMyCollectionChanged)

                ' Bind the root StackPanel element to the collection
                ' related object binding paths are defined in the XAML.
                Me.LayoutRoot.DataContext = trackedCustomers
                Me.LayoutRoot.UpdateLayout()
        Catch ex As DataServiceQueryException
            MessageBox.Show("The query could not be completed:\n" + ex.ToString())
        Catch ex As InvalidOperationException
            MessageBox.Show("The following error occurred:\n" + ex.ToString())
        End Try
    End Sub
    ' Method that is called when the CollectionChanged event is handled.
    Private Function OnMyCollectionChanged( _
        ByVal entityCollectionChangedinfo As EntityCollectionChangedParams) As Boolean
        If entityCollectionChangedinfo.Action = _
            NotifyCollectionChangedAction.Remove Then

            ' Delete the related items when an order is deleted.
            If entityCollectionChangedinfo.TargetEntity.GetType() Is GetType(Orders) Then

                ' Get the context and object from the supplied parameter.
                Dim context = entityCollectionChangedinfo.Context
                Dim deletedOrder As Orders = _
                CType(entityCollectionChangedinfo.TargetEntity, Orders)

                ' Load the related OrderDetails.
                context.LoadProperty(deletedOrder, "Order_Details")

                ' Delete the order and its related items
                For Each item As Order_Details In deletedOrder.Order_Details
                    'context.DeleteLink(deletedOrder, "Order_Details", item)
                    context.DeleteObject(item)
                Next

                ' Delete the order and then return false since the object is already deleted.
                context.DeleteObject(deletedOrder)

                Return False
            Else
                Return True
            End If
        Else
            ' Use the default behavior.
            Return True
        End If
    End Function
    ' Method that is called when the PropertyChanged event is handled.
    Private Function OnMyPropertyChanged( _
    ByVal entityChangedInfo As EntityChangedParams) As Boolean
        ' Validate a changed order to ensure that changes are not made 
        ' after the order ships.
        If entityChangedInfo.Entity.GetType() Is GetType(Orders) AndAlso _
            (CType(entityChangedInfo.Entity, Orders).ShippedDate < DateTime.Today) Then
            Throw New ApplicationException(String.Format( _
                "The order {0} cannot be changed because it shipped on {1}.", _
                CType(entityChangedInfo.Entity, Orders).OrderID, _
                CType(entityChangedInfo.Entity, Orders).ShippedDate))
            Return True
        End If
    End Function
    Private Sub deleteButton_Click(ByVal sender As Object, ByVal e As RoutedEventArgs)
        ' Get the Orders binding collection.
        Dim trackedOrders As DataServiceCollection(Of Orders) = _
            (CType(customerIDComboBox.SelectedItem, Customers)).Orders

        ' Remove the currently selected order.
        trackedOrders.Remove(CType(ordersDataGrid.SelectedItem, Orders))
    End Sub
    Private Sub saveChangesButton_Click(ByVal sender As Object, ByVal e As RoutedEventArgs)
        Try
            ' Save changes to the data service.
            context.SaveChanges()
        Catch ex As Exception
            MessageBox.Show(ex.ToString())
        End Try
    End Sub
End Class

El siguiente código XAML define la ventana del ejemplo anterior.

<Window x:Class="CustomerOrdersCustom"
             xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
             xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
             Height="423" Width="679" Loaded="Window_Loaded" >
    <StackPanel Orientation="Vertical" Height="Auto" Name="LayoutRoot" Width="Auto">
        <Label Content="Customer ID" Margin="20,0,0,0" />
        <ComboBox Name="customerIDComboBox" DisplayMemberPath="CustomerID" ItemsSource="{Binding}" 
                  IsSynchronizedWithCurrentItem="True" SelectedIndex="0" Height="23" Width="120" 
                  HorizontalAlignment="Left" Margin="20,0,0,0" VerticalAlignment="Center" />
        <ListView ItemsSource="{Binding Path=Orders}" Name="ordersDataGrid" Margin="34,46,34,50">
            <ListView.View>
                <GridView AllowsColumnReorder="False" ColumnHeaderToolTip="Line Items">
                    <GridViewColumn DisplayMemberBinding="{Binding Path=OrderID, Mode=OneWay}" 
                        Header="Order ID" Width="50"/>
                    <GridViewColumn DisplayMemberBinding="{Binding Path=OrderDate, Mode=TwoWay}" 
                        Header="Order Date" Width="50"/>
                    <GridViewColumn DisplayMemberBinding="{Binding Path=Freight, Mode=TwoWay}" 
                        Header="Freight Cost" Width="50"/>
                </GridView>
            </ListView.View>
        </ListView>
        <StackPanel Orientation="Horizontal">
            <Button Name="deleteButton" Content="Delete Order" Click="deleteButton_Click" 
                Width="80" Height="30" Margin="450,0,10,0"/>
            <Button Name="saveChangesButton" Content="Save Changes" Click="saveChangesButton_Click" 
                Width="80" Height="30" Margin="10,0,0,0"/>
        </StackPanel>
    </StackPanel>
</Window>

Propiedades

Context	El contexto asociado al objeto entidad que ha cambiado.
Entity	El objeto entidad que ha cambiado.
PropertyName	Nombre de la propiedad en el objeto entidad que hace referencia al objeto de destino.
PropertyValue	El objeto al que hace referencia actualmente la propiedad cambiada en el objeto entidad.
SourceEntitySet	El conjunto de entidades del objeto de origen.
TargetEntitySet	El conjunto de entidades al que pertenece el objeto de entidad de destino.

Métodos

Equals(Object)	Determina si el objeto especificado es igual que el objeto actual. (Heredado de Object)
GetHashCode()	Sirve como la función hash predeterminada. (Heredado de Object)
GetType()	Obtiene el Type de la instancia actual. (Heredado de Object)
MemberwiseClone()	Crea una copia superficial del Object actual. (Heredado de Object)
ToString()	Devuelve una cadena que representa el objeto actual. (Heredado de Object)

Consulte también

• Enlazar datos a controles (Servicios de datos de WCF)
• Cómo: Personalizar comportamientos de enlace de datos (Servicios de datos de WCF)