How to: Add Query Options to a Data Service Query (WCF Data Services)
Important
WCF Data Services has been deprecated and will no longer be available for download from the Microsoft Download Center. WCF Data Services supported earlier versions of the Microsoft OData (V1-V3) protocol only and has not been under active development. OData V1-V3 has been superseded by OData V4, which is an industry standard published by OASIS and ratified by ISO. OData V4 is supported through the OData V4 compliant core libraries available at Microsoft.OData.Core. Support documentation is available at OData.Net, and the OData V4 service libraries are available at Microsoft.AspNetCore.OData.
RESTier is the successor to WCF Data Services. RESTier helps you bootstrap a standardized, queryable, HTTP-based REST interface in minutes. Like WCF Data Services before it, Restier provides simple and straightforward ways to shape queries and intercept submissions before and after they hit the database. And like Web API + OData, you still have the flexibility to add your own custom queries and actions with techniques you're already familiar with.
WCF Data Services enables you to query a data service from a .NET Framework-based client application by using the generated client data service classes. The easiest to do this is to compose a Language Integrated Query (LINQ) query expression that includes the desired query options. You can also call a series of LINQ query methods to compose an equivalent query. Finally, you can use the AddQueryOption method to add query options to a query. In each of these cases, the URI that is generated by the client includes the requested entity set with the selected query options applied. For more information, see Querying the Data Service.
The example in this topic uses the Northwind sample data service and autogenerated client data service classes. This service and the client data classes are created when you complete the WCF Data Services quickstart.
Example
The following example shows how to compose a LINQ query expression that returns only orders with a freight cost of more than $30 and that orders the results by the ship date in descending order.
// Create the DataServiceContext using the service URI.
NorthwindEntities context = new NorthwindEntities(svcUri);
// Define a query for orders with a Freight value greater than 30
// and that is ordered by the ship date, descending.
var selectedOrders = from o in context.Orders
where o.Freight > 30
orderby o.ShippedDate descending
select o;
try
{
// Enumerate over the results of the query.
foreach (Order order in selectedOrders)
{
Console.WriteLine("Order ID: {0} - Ship Date: {1} - Freight: {2}",
order.OrderID, order.ShippedDate, order.Freight);
}
}
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)
' Define a query for orders with a Freight value greater than 30
' and that is ordered by the ship date, descending.
Dim selectedOrders = From o In context.Orders _
Where (o.Freight > 30) _
Order By o.ShippedDate Descending _
Select o
Try
' Enumerate over the results of the query.
For Each order As Order In selectedOrders
Console.WriteLine("Order ID: {0} - Ship Date: {1} - Freight: {2}", _
order.OrderID, order.ShippedDate, order.Freight)
Next
Catch ex As DataServiceQueryException
Throw New ApplicationException( _
"An error occurred during query execution.", ex)
End Try
Example
The following example shows how to compose a LINQ query by using LINQ query methods that is equivalent to the previous query.
// Create the DataServiceContext using the service URI.
NorthwindEntities context = new NorthwindEntities(svcUri);
// Define a query for orders with a Freight value greater than 30
// and that is ordered by the ship date, descending.
var selectedOrders = context.Orders
.Where(o => o.Freight > 30)
.OrderByDescending(o => o.ShippedDate);
try
{
// Enumerate over the results of the query.
foreach (Order currentOrder in selectedOrders)
{
Console.WriteLine("Order ID: {0} - Ship Date: {1} - Freight: {2}",
currentOrder.OrderID, currentOrder.ShippedDate,
currentOrder.Freight);
}
}
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)
' Define a query for orders with a Freight value greater than 30
' and that is ordered by the ship date, descending.
Dim selectedOrders = context.Orders _
.Where(Function(o) o.Freight.Value > 30) _
.OrderByDescending(Function(o) o.ShippedDate)
Try
' Enumerate over the results of the query.
For Each order As Order In selectedOrders
Console.WriteLine("Order ID: {0} - Ship Date: {1} - Freight: {2}", _
order.OrderID, order.ShippedDate, order.Freight)
Next
Catch ex As DataServiceQueryException
Throw New ApplicationException( _
"An error occurred during query execution.", ex)
End Try
Example
The following example shows how to use to the AddQueryOption method to create a DataServiceQuery<TElement> that is equivalent to the previous examples.
// Create the DataServiceContext using the service URI.
NorthwindEntities context = new NorthwindEntities(svcUri);
// Define a query for orders with a Freight value greater than 30
// and that is ordered by the ship date, descending.
DataServiceQuery<Order> selectedOrders = context.Orders
.AddQueryOption("$filter", "Freight gt 30")
.AddQueryOption("$orderby", "OrderID desc");
try
{
// Enumerate over the results of the query.
foreach (Order order in selectedOrders)
{
Console.WriteLine("Order ID: {0} - Ship Date: {1} - Freight: {2}",
order.OrderID, order.ShippedDate, order.Freight);
}
}
catch (DataServiceQueryException ex)
{
throw new ApplicationException(
"An error occurred during query execution.", ex);
}
' Create the DataServiceContext using the service URI.
Dim context = New NorthwindEntities(svcUri)
' Define a query for orders with a Freight value greater than 30
' and that is ordered by the ship date, descending.
Dim selectedOrders As DataServiceQuery(Of Order) = context.Orders _
.AddQueryOption("$filter", "Freight gt 30") _
.AddQueryOption("$orderby", "OrderID desc")
Try
' Enumerate over the results of the query.
For Each order As Order In selectedOrders
Console.WriteLine("Order ID: {0} - Ship Date: {1} - Freight: {2}", _
order.OrderID, order.ShippedDate, order.Freight)
Next
Catch ex As DataServiceQueryException
Throw New ApplicationException( _
"An error occurred during query execution.", ex)
End Try
Example
The following example shows how to use the $orderby query option to both filter and order returned Orders objects by the Freight property.
// Create the DataServiceContext using the service URI.
NorthwindEntities context = new NorthwindEntities(svcUri);
// Define a query for orders with a Freight value greater than 30
// that also orders the result by the Freight value, descending.
DataServiceQuery<Order> selectedOrders = context.Orders
.AddQueryOption("$orderby", "Freight gt 30 desc");
try
{
// Enumerate over the results of the query.
foreach (Order order in selectedOrders)
{
Console.WriteLine("Order ID: {0} - Freight: {1}",
order.OrderID, order.Freight);
}
}
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)
' Define a query for orders with a Freight value greater than 30
' that also orders the result by the Freight value, descending.
Dim selectedOrders As DataServiceQuery(Of Order) = _
context.Orders.AddQueryOption("$orderby", "Freight gt 30 desc")
Try
' Enumerate over the results of the query.
For Each order As Order In selectedOrders
Console.WriteLine("Order ID: {0} - Freight: {1}", _
order.OrderID, order.Freight)
Next
Catch ex As DataServiceQueryException
Throw New ApplicationException( _
"An error occurred during query execution.", ex)
End Try