BeforeSetAttribute Class

Marks an action to be performed in a property setter before the value is written to the backing store.

Syntax

Visual Basic
C#

'Declaration
 
<AttributeUsageAttribute(ValidOn=AttributeTargets.Method, 
   AllowMultiple=True, 
   Inherited=True)>
Public Class BeforeSetAttribute 
   Inherits PropertyInterceptorAttribute
   Implements System.Runtime.InteropServices._Attribute

'Usage
 
Dim instance As BeforeSetAttribute

[AttributeUsage(ValidOn=AttributeTargets.Method, 
   AllowMultiple=true, 
   Inherited=true)]
public class BeforeSetAttribute : PropertyInterceptorAttribute, System.Runtime.InteropServices._Attribute

Remarks

Use BeforeSet to specify one or more actions to be performed when a property setter is invoked. These actions occur before the backing value is stored. Actions may be defined as instance or static methods on a base or derived type. The execution order may be specified by using the Order named parameter. See the Developer's Guide for more information on action chaining and ordering. BeforeSet interceptor actions are automatically discovered the first time a property setter is called.

There are a number of acceptable signatures for methods marked with this attribute. In general, you can accept (or accept and return) an object of the expected property type, or accept one of the many derivations of PropertyInterceptorArgs. See the examples provided with the constructors for more information. If a signature is invalid, you will receive a PropertyInterceptorException when DevForce either builds or tries to execute the method, depending on when the error is detected.

Example

public partial class Customer {

  // Sample signatures for a BeforeSet method for any Customer property
  // (invoked for both simple and navigation properties).
  // Additional signatures are possible.

  // Signature 1 - accept a property value and return a property value.
  // Any value returned is passed to next action.
  [BeforeSet]
  public object BeforeSetAnyCustomerProperty1(object value) {
    Console.WriteLine("Before setting a customer property 1");
    return value;
  }

  // Signature 2 - accept a property value, but no return value.
  [BeforeSet]
  public void BeforeSetAnyCustomerProperty2(object value) {
    Console.WriteLine("Before setting a customer property 2");
  }

  // Signature 3 - accept base IPropertyInterceptorArgs.
  // Allows you to cancel further actions and modify the Value.
  // No property information available.
  [BeforeSet]
  public void BeforeSetAnyCustomerProperty3(IPropertyInterceptorArgs args) {
    Console.WriteLine("Before setting a customer property 3");
  }

  // Signature 4 - accept EntityProperty interceptor arguments.
  // The arguments passed allow you to determine the property retrieved
  // and to cancel the set.  args.Value can be modified.
  // args.VerificationSetterOptions allows verification options to be set for all subsequent
  // actions within the setter.  Note that verification can be turned off also.
  [BeforeSet]
  public void BeforeSetAnyCustomerProperty4(IEntityPropertySetInterceptorArgs args) {
    Console.WriteLine("Before setting a customer property 4");
  }

  // Signature 5 - accept strongly-typed IPropertyInterceptorArgs.
  // Same features as IPropertyInterceptorArgs but Instance is now strongly-typed.
  [BeforeSet]
  public void BeforeSetAnyCustomerProperty5(IPropertyInterceptorArgs<Customer, object> args) {
    Console.WriteLine("Before setting a customer property 5");
  }
}

Inheritance Hierarchy

System.Object
   System.Attribute
      IdeaBlade.Core.PropertyInterceptorAttribute
         IdeaBlade.Core.BeforeSetAttribute

Requirements

Target Platforms: Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

Reference

BeforeSetAttribute Members
IdeaBlade.Core Namespace
PropertyInterceptorArgs Class
PropertyInterceptorAction Class