DataServiceCollection<T>.Continuation 属性
获取用于返回下一分页结果集的延续对象。
命名空间： System.Data.Services.Client
程序集： Microsoft.Data.Services.Client（在 Microsoft.Data.Services.Client.dll 中）
语法
声明
Public Property Continuation As DataServiceQueryContinuation(Of T)
Get
Set
用法
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>)
属性值
类型：System.Data.Services.Client.DataServiceQueryContinuation<T>
DataServiceQueryContinuation<T> 对象，包含用于返回下一分页结果集的 URI。
注释
在数据服务中启用分页时，Continuation 属性将返回用于访问下一分页结果集的链接。 有关详细信息，请参阅配置数据服务（WCF 数据服务）。
将分页结果加载到 DataServiceCollection<T> 中时，必须通过传递从 Continuation 属性获取的 URI 的执行结果，调用 DataServiceCollection<T> 的 Load(IEnumerable<T>) 方法来显式加载各页。
示例
下面的示例摘自在 WPF 中定义 SalesOrders 窗口的可扩展应用程序标记语言 (XAML) 页的代码隐藏页。 加载此窗口时，会根据查询结果创建 DataServiceCollection<T>，该查询将返回客户，并按国家/地区进行筛选。 将加载此分页结果的所有页面和相关订单，并将这些页面绑定到作为 WPF 窗口的根布局控件的 StackPanel 的 DataContext 属性。 有关详细信息，请参阅如何：将数据绑定到 Windows Presentation Foundation 元素（WCF 数据服务）。
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());
}
}
}
}
请参阅
参考
System.Data.Services.Client 命名空间