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DataServiceCollection<T>.Continuation Propiedad

Obtiene un objeto de continuación que se usa para devolver el conjunto siguiente de resultados paginados.

Espacio de nombres:  System.Data.Services.Client
Ensamblado:  Microsoft.Data.Services.Client (en Microsoft.Data.Services.Client.dll)

Sintaxis

'Declaración
Public Property Continuation As DataServiceQueryContinuation(Of T)
    Get
    Set
'Uso
Dim instance As DataServiceCollection
Dim value As DataServiceQueryContinuation(Of T)

value = instance.Continuation

instance.Continuation = value
public DataServiceQueryContinuation<T> Continuation { get; set; }
public:
property DataServiceQueryContinuation<T>^ Continuation {
    DataServiceQueryContinuation<T>^ get ();
    void set (DataServiceQueryContinuation<T>^ value);
}
member Continuation : DataServiceQueryContinuation<'T> with get, set
function get Continuation () : DataServiceQueryContinuation<T>
function set Continuation (value : DataServiceQueryContinuation<T>)

Valor de la propiedad

Tipo: System.Data.Services.Client.DataServiceQueryContinuation<T>
Objeto DataServiceQueryContinuation<T> que contiene el URI para devolver el conjunto siguiente de resultados paginados.

Comentarios

La propiedad Continuation devuelve un vínculo que se usa para obtener acceso al conjunto siguiente de resultados paginados cuando la paginación está habilitada en el servicio de datos. Para obtener más información, vea Configurar el servicio de datos (WCF Data Services).

Al cargar un resultado paginado en DataServiceCollection<T>, debe cargar las páginas explícitamente llamando al método Load(IEnumerable<T>) en DataServiceCollection<T> pasando el resultado de la ejecución del URI que se obtuvo de la propiedad Continuation.

Ejemplos

El ejemplo siguiente corresponde a la página de código subyacente de una página de lenguaje XAML que define la ventana SalesOrders en WPF. Cuando se carga la ventana, se crea una DataServiceCollection<T> dependiendo del resultado de una consulta que devuelve los clientes filtrados por país. Se cargan todas las páginas de este resultado paginado, junto con los pedidos relacionados, y se enlazan a la propiedad DataContext de StackPanel que es el control de diseño raíz para la ventana de WPF. Para obtener más información, vea Cómo: Enlazar datos a los elementos de Windows Presentation Foundation (WCF Data Services).

Imports System
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

Partial Public Class CustomerOrdersWpf3
    Inherits Window

    Private context As NorthwindEntities
    Private trackedCustomers As DataServiceCollection(Of Customer)
    Private Const customerCountry As String = "Germany"
    Private Const svcUri As String = "https://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 _
                                    Where cust.Country = customerCountry _
                                    Select cust

                ' Create a new collection for binding based on the LINQ query.
            trackedCustomers = New DataServiceCollection(Of Customer)(customerQuery)

                ' Load all pages of the response at once.
            While trackedCustomers.Continuation IsNot Nothing
                trackedCustomers.Load( _
                        context.Execute(Of Customer)(trackedCustomers.Continuation.NextLinkUri))
            End While

            ' 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
    Private Sub customerIDComboBox_SelectionChanged(ByVal sender As Object, ByVal e As SelectionChangedEventArgs)
        Dim selectedCustomer As Customer = _
            CType(Me.customerIDComboBox.SelectedItem, Customer)
        Try
            If selectedCustomer.Orders.Count = 0 Then
                ' Load the first page of related orders for the selected customer.
                context.LoadProperty(selectedCustomer, "Orders")
            End If

            ' Load all remaining pages.
            While selectedCustomer.Orders.Continuation IsNot Nothing
                selectedCustomer.Orders.Load( _
                        context.Execute(Of Order)(selectedCustomer.Orders.Continuation.NextLinkUri))
            End While
        Catch ex As Exception
            MessageBox.Show(ex.ToString())
        End Try
    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
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Navigation;
using System.Windows.Shapes;
using System.Data.Services.Client;
using NorthwindClient.Northwind;

namespace NorthwindClient
{
    public partial class CustomerOrdersWpf3 : Window
    {
        private NorthwindEntities context;
        private DataServiceCollection<Customer> trackedCustomers;
        private const string customerCountry = "Germany";
        private const string svcUri = "https://localhost:12345/Northwind.svc/";

        public CustomerOrdersWpf3()
        {
            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
                                    where cust.Country == customerCountry
                                    select cust;

                // Create a new collection for binding based on the LINQ query.
                trackedCustomers = new DataServiceCollection<Customer>(customerQuery);

                // Load all pages of the response at once.
                while (trackedCustomers.Continuation != null)
                {
                    trackedCustomers.Load(
                        context.Execute<Customer>(trackedCustomers.Continuation.NextLinkUri));
                }

                // 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());
            }
        }

        private void customerIDComboBox_SelectionChanged(object sender, SelectionChangedEventArgs e)
        {
            Customer selectedCustomer = 
                this.customerIDComboBox.SelectedItem as Customer;

            try
            {
                // Load the first page of related orders for the selected customer.
                context.LoadProperty(selectedCustomer, "Orders");

                // Load all remaining pages.
                while (selectedCustomer.Orders.Continuation != null)
                {
                    selectedCustomer.Orders.Load(
                        context.Execute<Order>(selectedCustomer.Orders.Continuation.NextLinkUri));
                }
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.ToString());
            }
        }

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

Vea también

Referencia

DataServiceCollection<T> Clase

Espacio de nombres System.Data.Services.Client

Otros recursos

Cargar contenido aplazado (WCF Data Services)

Enlazar datos a controles (WCF Data Services)