QueryInterceptorAttribute Class

Artigo
05/29/2013

The QueryInterceptorAttribute on a method annotates it as a query interceptor on the specified entity set.

Inheritance Hierarchy

System.Object
System.Attribute
System.Data.Services.QueryInterceptorAttribute

Namespace: System.Data.Services
Assembly: Microsoft.Data.Services (in Microsoft.Data.Services.dll)

Syntax

'Declaration
<AttributeUsageAttribute(AttributeTargets.Method, AllowMultiple := True, Inherited := True)> _
Public NotInheritable Class QueryInterceptorAttribute _
    Inherits Attribute
'Usage
Dim instance As QueryInterceptorAttribute

[AttributeUsageAttribute(AttributeTargets.Method, AllowMultiple = true, Inherited = true)]
public sealed class QueryInterceptorAttribute : Attribute

[AttributeUsageAttribute(AttributeTargets::Method, AllowMultiple = true, Inherited = true)]
public ref class QueryInterceptorAttribute sealed : public Attribute

[<SealedAttribute>]
[<AttributeUsageAttribute(AttributeTargets.Method, AllowMultiple = true, Inherited = true)>]
type QueryInterceptorAttribute =  
    class 
        inherit Attribute 
    end

public final class QueryInterceptorAttribute extends Attribute

The QueryInterceptorAttribute type exposes the following members.

Constructors

	Name	Description
	QueryInterceptorAttribute	Initializes a new instance of the QueryInterceptorAttribute class for the entity set specified by the entitySetName parameter.

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Properties

	Name	Description
	EntitySetName	Gets the name of the entity set that contains the entity to which the interceptor applies.
	TypeId	(Inherited from Attribute.)

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Methods

	Name	Description
	Equals	(Inherited from Attribute.)
	GetHashCode	(Inherited from Attribute.)
	GetType	(Inherited from Object.)
	IsDefaultAttribute	(Inherited from Attribute.)
	Match	(Inherited from Attribute.)
	ToString	(Inherited from Object.)

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Explicit Interface Implementations

	Name	Description
	_Attribute.GetIDsOfNames	(Inherited from Attribute.)
	_Attribute.GetTypeInfo	(Inherited from Attribute.)
	_Attribute.GetTypeInfoCount	(Inherited from Attribute.)
	_Attribute.Invoke	(Inherited from Attribute.)

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Remarks

Entity set-level authorization and validation is implemented by methods annotated with the QueryInterceptorAttribute. WCF Data Servicess do not implement security policies but instead provide the infrastructure required for service developers to write their own security rules and business validation.

Entity set access control and validation is enabled through query operations by using query composition. To control entity-based access, implement a method-per-entity set according to the following rules:

The method must have public scope and be annotated with the QueryInterceptorAttribute, taking the name of a entity set as a parameter.

The method must accept no parameters.

The method must return an expression of type Expression<Func<T, bool>> that is the filter to be composed for the entity set.

Examples

The following example controls access to the Customers entity set. Each Customer can only see Orders associated with that Customer.

[QueryInterceptor("Orders")]
public Expression<Func<Order, bool>> FilterOrders() 
{
    return o => o.Customer.Name == /* Current principal name. */;
} 
 
// Insures that the user accessing the customer(s) has the appropriate
// rights as defined in the QueryRules object to access the customer
// resource(s).
 
[QueryInterceptor ("Customers")]
public Expression<Func<Customer, bool>> FilterCustomers() 
{
  return c => c.Name == /* Current principal name. */ &&
              this.CurrentDataSource.QueryRules.Contains(
                rule => rule.Name == c.Name &&
                        rule.CustomerAllowedToQuery == true
              );
}

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.

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