EntityQuery Class

[WCF RIA Services Version 1 Service Pack 2 is compatible with either .NET framework 4 or .NET Framework 4.5, and with either Silverlight 4 or Silverlight 5.]

Represents a query method invocation.

Inheritance Hierarchy


Namespace:  System.ServiceModel.DomainServices.Client
Assembly:  System.ServiceModel.DomainServices.Client (in System.ServiceModel.DomainServices.Client.dll)


Public MustInherit Class EntityQuery
Dim instance As EntityQuery
public abstract class EntityQuery
public ref class EntityQuery abstract
type EntityQuery =  class end
public abstract class EntityQuery

The EntityQuery type exposes the following members.


  Name Description
Public property DomainClient Gets the DomainClient for this query.
Public property EntityType Gets the type this query retrieves data from.
Public property HasSideEffects Gets a value indicating whether the query has side-effects.
Public property IncludeTotalCount Gets or sets a value indicating whether the TotalEntityCount property is required.
Public property IsComposable Gets a value indicating if the query supports composition.
Public property Parameters Gets the parameters required by the query method.
Public property Query Gets the underlying IQueryable for the query.
Public property QueryName Gets the name of the query method.



  Name Description
Public method Equals (Inherited from Object.)
Protected method Finalize (Inherited from Object.)
Public method GetHashCode (Inherited from Object.)
Public method GetType (Inherited from Object.)
Protected method MemberwiseClone (Inherited from Object.)
Public method ToString (Inherited from Object.)



In your client application, you can apply additional filtering on a query to limit which entities are returned. You use LINQ and a subset of LINQ query operators to modify the results returned from the query. The following lists the available query operators:

  • Where

  • OrderBy

  • ThenBy

  • Skip

  • Take

After you apply additional filtering, you pass the EntityQuery object as a parameter in the Load method to execute the query and get the results. If the query has a QueryAttribute with the IsComposable property set to false, you cannot apply additional filtering on the query. Generally, only queries that return a single entity will have IsComposable set to false.


The following code shows how to retrieve customers from the domain service. It filters customers who have phone numbers that start with 583 and orders them alphabetically by LastName. The results are displayed in a DataGrid.

Partial Public Class MainPage
    Inherits UserControl

    Private _customerContext As New CustomerDomainContext

    Public Sub New()

        Dim query As EntityQuery(Of Customer)

        query = _
            From c In Me._customerContext.GetCustomersQuery() _
            Where c.Phone.StartsWith("583") _
            Order By c.LastName

        Dim loadOp = Me._customerContext.Load(query)
        CustomerGrid.ItemsSource = loadOp.Entities
    End Sub

End Class
public partial class MainPage : UserControl
    private CustomerDomainContext _customerContext = new CustomerDomainContext();

    public MainPage()
        EntityQuery<Customer> query = 
            from c in _customerContext.GetCustomersQuery()
            where c.Phone.StartsWith("583")
            orderby c.LastName
            select c;
        LoadOperation<Customer> loadOp = this._customerContext.Load(query);
        CustomerGrid.ItemsSource = loadOp.Entities;

Thread Safety

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

See Also


System.ServiceModel.DomainServices.Client Namespace