DataServiceContext.Execute 方法

public:
generic <typename T>
 System::Data::Services::Client::QueryOperationResponse<T> ^ Execute(System::Data::Services::Client::DataServiceQueryContinuation<T> ^ continuation);

public System.Data.Services.Client.QueryOperationResponse<T> Execute<T> (System.Data.Services.Client.DataServiceQueryContinuation<T> continuation);

member this.Execute : System.Data.Services.Client.DataServiceQueryContinuation<'T> -> System.Data.Services.Client.QueryOperationResponse<'T>

Public Function Execute(Of T) (continuation As DataServiceQueryContinuation(Of T)) As QueryOperationResponse(Of T)

类型参数

参数

返回

包含查询结果中下一页数据的响应。

例外

注解

所提供的 DataServiceQueryContinuation<T> 对象所包含的 URI 在执行时会返回查询结果中的下一页数据。

public:
generic <typename TElement>
 System::Collections::Generic::IEnumerable<TElement> ^ Execute(Uri ^ requestUri);

public System.Collections.Generic.IEnumerable<TElement> Execute<TElement> (Uri requestUri);

member this.Execute : Uri -> seq<'Element>

Public Function Execute(Of TElement) (requestUri As Uri) As IEnumerable(Of TElement)

类型参数

参数

返回

查询操作的结果。

例外

示例

下面的示例使用 do…while 循环从数据服务的分页结果中加载 Customers 实体。 通过使用下一链接 URI 调用 Execute 方法来接收下一页数据。

// Create the DataServiceContext using the service URI.
NorthwindEntities context = new NorthwindEntities(svcUri);
DataServiceQueryContinuation<Customer> token = null;
int pageCount = 0;

try
{
    // Execute the query for all customers and get the response object.
    QueryOperationResponse<Customer> response =
        context.Customers.Execute() as QueryOperationResponse<Customer>;

    // With a paged response from the service, use a do...while loop
    // to enumerate the results before getting the next link.
    do
    {
        // Write the page number.
        Console.WriteLine("Page {0}:", pageCount++);

        // If nextLink is not null, then there is a new page to load.
        if (token != null)
        {
            // Load the new page from the next link URI.
            response = context.Execute<Customer>(token)
                as QueryOperationResponse<Customer>;
        }

        // Enumerate the customers in the response.
        foreach (Customer customer in response)
        {
            Console.WriteLine("\tCustomer Name: {0}", customer.CompanyName);
        }
    }

    // Get the next link, and continue while there is a next link.
    while ((token = response.GetContinuation()) != null);
}
catch (DataServiceQueryException ex)
{
    throw new ApplicationException(
        "An error occurred during query execution.", ex);
}

' Create the DataServiceContext using the service URI.
Dim context = New NorthwindEntities(svcUri)
Dim token As DataServiceQueryContinuation(Of Customer) = Nothing
Dim pageCount = 0

Try
    ' Execute the query for all customers and get the response object.
    Dim response As QueryOperationResponse(Of Customer) = _
        CType(context.Customers.Execute(), QueryOperationResponse(Of Customer))

    ' With a paged response from the service, use a do...while loop 
    ' to enumerate the results before getting the next link.
    Do
        ' Write the page number.
        Console.WriteLine("Page {0}:", pageCount + 1)

        ' If nextLink is not null, then there is a new page to load.
        If token IsNot Nothing Then
            ' Load the new page from the next link URI.
            response = CType(context.Execute(Of Customer)(token),  _
            QueryOperationResponse(Of Customer))
        End If

        ' Enumerate the customers in the response.
        For Each customer As Customer In response
            Console.WriteLine(vbTab & "Customer Name: {0}", customer.CompanyName)
        Next

        ' Get the next link, and continue while there is a next link.
        token = response.GetContinuation()
    Loop While token IsNot Nothing
Catch ex As DataServiceQueryException
    Throw New ApplicationException( _
            "An error occurred during query execution.", ex)
End Try

注解

Execute 方法用于通过 URI 查询数据服务；该方法会导致将 HTTP GET 请求发送给数据服务。 指定的请求 URI 可为绝对值或相对值。

如果 requestUri 为绝对值，则此方法用于验证 URI 是否指向构造 DataServiceContext 时所指定的数据服务。 如果 requestUri 为相对值，则此方法会将构造 requestUri 时所提供的内容与任何前导斜杠剥离并对其追加 DataServiceContext。 将在传递给 DataServiceContext 构造函数的 URI 后面追加斜杠（如果斜杠不存在）。

此方法返回时，已从网络流读取请求的所有 HTTP 响应，但尚未对响应进行处理；没有标识解析或对象具体化。 在枚举响应中的指定实体之前，尚未对该实体进行标识解析或完全对象具体化操作。

另请参阅

• 加载延迟的内容（WCF 数据服务）
• 如何：加载分页结果（WCF 数据服务）