DataServiceCollection<T>.Continuation Properti
Definisi
Penting
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Mendapatkan objek kelanjutan yang digunakan untuk mengembalikan kumpulan hasil halaman berikutnya.
public:
property System::Data::Services::Client::DataServiceQueryContinuation<T> ^ Continuation { System::Data::Services::Client::DataServiceQueryContinuation<T> ^ get(); void set(System::Data::Services::Client::DataServiceQueryContinuation<T> ^ value); };
public System.Data.Services.Client.DataServiceQueryContinuation<T> Continuation { get; set; }
member this.Continuation : System.Data.Services.Client.DataServiceQueryContinuation<'T> with get, set
Public Property Continuation As DataServiceQueryContinuation(Of T)
Nilai Properti
Objek DataServiceQueryContinuation<T> yang berisi URI untuk mengembalikan kumpulan hasil halaman berikutnya.
Contoh
Contoh berikut berasal dari halaman code-behind untuk halaman Extensible Application Markup Language (XAML) yang menentukan SalesOrders
jendela di WPF. Saat jendela dimuat, DataServiceCollection<T> dibuat berdasarkan hasil kueri yang mengembalikan pelanggan, difilter menurut negara/wilayah. Semua halaman hasil halaman ini dimuat, bersama dengan pesanan terkait, dan terikat ke DataContext properti dari StackPanel yang merupakan kontrol tata letak akar untuk jendela WPF. Untuk informasi selengkapnya, lihat Cara: Mengikat Data ke Elemen Windows Presentation Foundation.
using System;
using System.Data.Services.Client;
using System.Linq;
using System.Windows;
using System.Windows.Controls;
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 = "http://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());
}
}
}
}
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 = "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 _
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
Keterangan
Properti Continuation mengembalikan tautan yang digunakan untuk mengakses kumpulan hasil halaman berikutnya saat halaman diaktifkan dalam layanan data. Untuk informasi selengkapnya, lihat Mengonfigurasi Layanan Data.
Saat memuat hasil halaman ke dalam DataServiceCollection<T>, Anda harus secara eksplisit memuat halaman dengan memanggil Load(IEnumerable<T>) metode pada DataServiceCollection<T> dengan meneruskan hasil eksekusi URI yang diperoleh dari Continuation properti .
Berlaku untuk
Lihat juga
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