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

提供的 DataServiceQueryContinuation<T> 对象包含执行时返回查询结果中下一页数据的 URI。

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

此示例使用循环 do…while 从数据服务分页结果加载 Customers 实体。 Execute通过使用下一个链接 URI 来接收下一页的数据，调用该方法。

// 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

该方法 Execute 用于按 URI 查询数据服务;该方法会导致向数据服务发出 HTTP GET 请求。 指定的请求 URI 可以是绝对 URI 或相对 URI。

如果为绝对值 requestUri ，此方法将验证 URI 是否指向构造 DataServiceContext时指定的相同数据服务。 requestUri如果为相对值，此方法将去除任何前导斜杠，并在构造requestUri时追加DataServiceContext到提供的内容。 如果不存在斜杠，则会在传递给构造函数的 DataServiceContext URI 之后追加斜杠。

此方法返回时，请求的所有 HTTP 响应已从网络流中读取，但不会处理响应;没有标识解析或对象具体化。 在枚举指定实体之前，不会对响应中的指定实体进行标识解析和完整对象具体化。

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）