Procédure : exécuter des requêtes dans un lot (WCF Data Services)
À l'aide de la bibliothèque cliente Services de données WCF , vous pouvez exécuter plusieurs requêtes sur le service de données dans un lot unique. Pour plus d'informations, consultez Opérations de traitement par lot (WCF Data Services).
L'exemple dans cette rubrique utilise l'exemple de service de données Northwind et des classes de service de données client générées automatiquement. Ce service et les classes de données clientes sont créés lorsque vous complétez le démarrage rapide WCF Data Services.
Exemple
L'exemple suivant montre comment appeler la méthode ExecuteBatch pour exécuter un tableau d'objets DataServiceRequest qui contient des requêtes qui retournent des objets Customers et Products du service de données Northwind. La collection d'objets QueryOperationResponse dans le DataServiceResponse retourné est énumérée, et la collection d'objets contenue dans chaque QueryOperationResponse est également énumérée.
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);
}
}
}