DataServiceCollection<T>.Continuation 屬性

發行項
04/13/2012

取得用於傳回下一組分頁式結果的接續物件。

命名空間： System.Data.Services.Client
組件： Microsoft.Data.Services.Client (在 Microsoft.Data.Services.Client.dll 中)

語法

'宣告
Public Property Continuation As DataServiceQueryContinuation(Of T)
    Get
    Set
'用途
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>)

屬性值

型別：System.Data.Services.Client.DataServiceQueryContinuation<T>
DataServiceQueryContinuation<T> 物件，其中包含用於傳回下一組分頁式結果的 URI。

備註

當資料服務中啟用分頁時，Continuation 屬性會傳回用於存取下一組分頁式結果的連結。如需詳細資訊，請參閱設定資料服務 (WCF Data Services)。

將分頁式結果載入到 DataServiceCollection<T> 時，您必須透過呼叫 DataServiceCollection<T> 上的 Load(IEnumerable<T>) 方法，傳遞從 Continuation 屬性取得的 URI 執行結果，明確載入頁面。

範例

下列範例取自用於定義 WPF 中 SalesOrders 視窗之可延伸應用程式標記語言 (XAML) 頁面的程式碼後置頁面。載入視窗時，會根據傳回客戶 (按國家 (地區) 排序) 查詢的結果建立 DataServiceCollection<T>。此分頁結果的所有頁面都會載入 (包含相關的訂單)，並且會繫結至 StackPanel (WPF 視窗的根配置控制項) 的 DataContext 屬性。如需詳細資訊，請參閱 HOW TO：將資料繫結至 Windows Presentation Foundation 項目 (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());
            }
        }
    }
}