Overview

Delegates in Microsoft Dynamics D365 are the methods for accessing elements in higher model  from a lower model & solving dependencies among models.Delegates serves as a contract between delegate instance & delegate handler.

For example

I have a scenario.I have 2 models i.e. Model A & Model B.In Model B i passed the reference of model A but vice-versa is not possible.It means i can call objects of model A in model B.But i cannot call objects of Model B in Model A.Here we can use delegates for accessing Model B values in Model A.

Sample Code & Explanation

1. Create a Model A & create a delegate.Delegate method should be empty and void type.[code language = “cpp”]
   public class MyClassInModelA
   {
   delegate void myDelegate(EventHandlerResult _result)
   {
   }
   }
   [/code]
2. Create a Model B & passed the reference of Model B using “Update Model Parameters”.It means i can call objects of model A.
3. Create a class in Model B & write a delegate handler.[code language = “cpp”]
   class MyClassInModelB
   {
   [SubscribesTo(classStr(MyClassInModelA), delegateStr(MyClassInModelA, myDelegate))]
   public static void myDelegateHandler(EventHandlerResult _result)
   {
   str ret = “Hi!This is Model B Values”;
   _result.result(ret);
   }
   }
   [/code]
4. Call the subscription of delegate in Model A & access the values of Model B in          Model A.In this way, i am calling Values of Model B in Model A without passing the reference of Model B in Model A.[code language = “cpp”]
   public class MyClassInModelA
   {

   delegate void myDelegate(EventHandlerResult _result)
   {
   }
   public static client server void main(Args args)
   {
   MyClassInModelA myClassInModelA = new MyClassInModelA();
   MyClassInModelA.myMethod();
   }
   public void myMethod()
   {
   EventHandlerResult result = new EventHandlerResult();
   this.myDelegate(result);
   str common = result.result();
   info(common);
   }
   }
   [/code]