방법: 일괄 처리로 쿼리 실행(WCF Data Services)

WCF Data Services 클라이언트 라이브러리를 사용하면 데이터 서비스에 대한 두 개 이상의 쿼리를 단일 일괄 처리로 실행할 수 있습니다. 자세한 내용은 일괄 처리 작업(WCF Data Services)을 참조하십시오.

이 항목의 예제에서는 Northwind 샘플 데이터 서비스 및 자동 생성된 클라이언트 데이터 서비스 클래스를 사용합니다. 이 서비스 및 클라이언트 데이터 클래스는 WCF Data Services 퀵 스타트를 완료하면 만들어집니다.

예

다음 예제에서는 Northwind 데이터 서비스에서 Customers 개체와 Products 개체를 모두 반환하는 쿼리가 포함된 DataServiceRequest<TElement> 개체 배열을 실행하는 ExecuteBatch 메서드를 호출하는 방법을 보여 줍니다. 반환된 DataServiceResponse의 QueryOperationResponse<T> 개체 컬렉션이 열거되고 각 QueryOperationResponse<T>에 포함되어 있는 개체 컬렉션도 열거됩니다.

Dim customerId = "ALFKI"

' Create the DataServiceContext using the service URI.
Dim context = New NorthwindEntities(svcUri)

' Create the separate query URI's, one that returns 
' a single customer and another that returns all Products.
Dim customerUri = New Uri(svcUri.AbsoluteUri & _
    "/Customers('" & customerId & "')/?$expand=Orders")
Dim productsUri = New Uri(svcUri.AbsoluteUri & _
       "/Products")

' Create the query requests.
Dim customerQuery = New DataServiceRequest(Of Customer)(customerUri)
Dim productsQuery = New DataServiceRequest(Of Product)(productsUri)

' Add the query requests to a batch request array.
Dim batchRequests = _
    New DataServiceRequest() {customerQuery, productsQuery}

Dim batchResponse As DataServiceResponse

Try
    ' Execute the query batch and get the response.
    batchResponse = context.ExecuteBatch(batchRequests)

    If batchResponse.IsBatchResponse Then
        ' Parse the batchResponse.BatchHeaders.
    End If

    ' Enumerate over the results of the query.
    For Each response As QueryOperationResponse In batchResponse
        ' Handle an error response.
        If response.StatusCode > 299 OrElse response.StatusCode < 200 Then
            Console.WriteLine("An error occurred.")
            Console.WriteLine(response.Error.Message)
        Else
            ' Find the response for the Customers query.
            If response.Query.ElementType Is GetType(Customer) Then
                For Each customer As Customer In response
                    Console.WriteLine("Customer: {0}", customer.CompanyName)
                    For Each order As Order In customer.Orders
                        Console.WriteLine("Order ID: {0} - Freight: {1}", _
                                order.OrderID, order.Freight)
                    Next
                Next
                ' Find the response for the Products query.
            ElseIf response.Query.ElementType Is GetType(Product) Then
                For Each product As Product In response
                    Console.WriteLine("Product: {0}", product.ProductName)
                Next
            End If
        End If
    Next
    ' This type of error is raised when the data service returns with
    ' a response code < 200 or >299 in the top level element.
Catch ex As DataServiceRequestException
    ' Get the response from the exception.
    batchResponse = ex.Response

    If (batchResponse.IsBatchResponse) Then
        ' Parse the batchResponse.BatchHeaders.
    End If
    For Each response As QueryOperationResponse In batchResponse
        If response.Error IsNot Nothing Then
            Console.WriteLine("An error occurred.")
            Console.WriteLine(response.Error.Message)
        End If
    Next
End Try

string customerId = "ALFKI";

// Create the DataServiceContext using the service URI.
NorthwindEntities context = new NorthwindEntities(svcUri);

// Create the separate query URI's, one that returns 
// a single customer and another that returns all Products.
Uri customerUri = new Uri(svcUri.AbsoluteUri + 
    "/Customers('" + customerId + "')/?$expand=Orders");
Uri productsUri = new Uri(svcUri.AbsoluteUri +
   "/Products");

// Create the query requests.
DataServiceRequest<Customer> customerQuery = 
    new DataServiceRequest<Customer>(customerUri);
DataServiceRequest<Product> productsQuery =
                new DataServiceRequest<Product>(productsUri);

// Add the query requests to a batch request array.
DataServiceRequest[] batchRequests = 
    new DataServiceRequest[]{customerQuery, productsQuery};

DataServiceResponse batchResponse;

try
{
    // Execute the query batch and get the response.
    batchResponse = context.ExecuteBatch(batchRequests);

    if (batchResponse.IsBatchResponse)
    {
        // Parse the batchResponse.BatchHeaders.
    }  
    // Enumerate over the results of the query.
    foreach (QueryOperationResponse response in batchResponse)
    {
        // Handle an error response.
        if (response.StatusCode > 299 || response.StatusCode < 200)
        {
            Console.WriteLine("An error occurred.");
            Console.WriteLine(response.Error.Message);
        }
        else
        {
            // Find the response for the Customers query.
            if (response.Query.ElementType == typeof(Customer))
            {
                foreach (Customer customer in response)
                {
                    Console.WriteLine("Customer: {0}", customer.CompanyName);
                    foreach (Order order in customer.Orders)
                    {
                        Console.WriteLine("Order ID: {0} - Freight: {1}",
                            order.OrderID, order.Freight);
                    }
                }
            }
            // Find the response for the Products query.
            else if (response.Query.ElementType == typeof(Product))
            {
                foreach (Product product in response)
                {
                    Console.WriteLine("Product: {0}", product.ProductName);
                }
            }
        }
    }
}

// This type of error is raised when the data service returns with
// a response code < 200 or >299 in the top level element.
catch (DataServiceRequestException e)
{
    // Get the response from the exception.
    batchResponse = e.Response;

    if (batchResponse.IsBatchResponse)
    {
        // Parse the batchResponse.BatchHeaders.
    }

    foreach (QueryOperationResponse response in batchResponse)
    {
        if (response.Error != null)
        {
            Console.WriteLine("An error occurred.");
            Console.WriteLine(response.Error.Message);
        }
    }
}

참고 항목

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데이터 클라이언트(WCF Data Services)