AOP Unity Interception

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AOP

It may be that I am going about this in the wrong way. I have implemented Unity Interception to handle my Logging and Exceptions. It works great, no logging or Exception Handling code in my domain.

I want to use the same strategy for Authorization and Validation. However I always run into the same issue: All the examples want to throw execptions when the pre-processing fails. All I want is to not execute the method, or prohibit access. In the example below, I prevent the method from being executed, but I always get a NullReferenceException. I believe the reason is that the method never gets invoked, therefore it is null. I don't want to do a try/catch around the method, this defeates the purpose of the Exception Handling I have in place. Suggestions?



Example:

internal class ValidationCallHandler : ICallHandler
 {
     public IMethodReturn Invoke(IMethodInvocation input, GetNextHandlerDelegate getNext)
     {
  // Preprocessing
         if (IsValidated())
         {
             return getNext()(input, getNext);
         }
 
        return input.CreateExceptionMethodReturn(new ValidationException());
     }
 
    private Boolean IsValidated()
     {
         return false;
     }
 

    public int Order { get; set; }
 }
 
[TestMethod]
 public void Be_Able_To_Validate_Account_Code_Setup()
 {
     AccountCodeSetup accountCodeSetup = _accountCodeSetupService.GetByName("Primary");
 
 // SaveAccountCodeSetupChanges is intercepted by the ValidationCallHandler
      _accountCodeSetupService.SaveAccountCodeSetupChanges(accountCodeSetup);
 }

Any suggestions?