Using X++ Delegates in the new Dynamics AX (aka AX 7)

In this post lets walk through an example on how we can use delegates in the new AX to develop customizations.

Quick summary of delegates: X++ delegates expose the publisher – subscriber pattern where a delegate defines a clear contract in a publisher class. It is a great way of encapsulating a piece of code. Delegates were introduced in AX 2012 couple of years back. With the new AX release delegates are the recommended way for customizing standard AX classes.

Let’s jump into action and customise standard AX sales order confirmation process. To keep it simple we will the change value of a field in confirmation journal table. The idea here is how to develop delegates and call them.

Confirmation journal header data is stored in CustConfirmJour table and it is initialised in the below class method during the sales confirmation posting process. Let’s modify it using delegates.

First we create a new delegate method in this class. This serves the purpose of defining a contract between the delegate instance and the delegate handler. There is no business logic inside the delegate method. Also notice that the delegates have return type as Void. In order to access the result value we have to pass EventHandlerResult object as a parameter.
 
 

 

 
Now we modify the actual method, declare the Event handler result object and call the delegate with the parameters in the method which we need to customise . The only customization in this method is 2 lines of code as highlighted below:
 
 

 

The class structure looks as below:


 Now we create the event handler method and this is where MS has done really nice stuff in moving the AX development environment to Visual Studio. Right click on the delegate method and copy the handler method definition.



Create a new class which will be used to subscribe to the delegate. So we create a new class, let call is salesConfirmJournalExt and paste the copied clipboard text
 
 

 


The delegate handler definition is automatically added with the below information:
 

 

Now we can add our custom code in this method. I just changed the purchase order field value and added some Infolog. Note that I am actually not returning anything in this method and not using the eventHandlerResult object really.

 So we are done. The see it wokring let\’s build the solution and confirm a sales order.

During the process the  Infolog messages we added in the delegate handler method are shown

The confirmation journal has the custom text appended to it in the field we used in our new class method.
 
 

Microsoft strongly recommends to use Delegates for customization due to all the good reasons of having minimum code changes in standard product. So try to use delegates to have a cleaner and manageable solutions.

Feel free to share your feedback.  Below are some good online references on Delegates:
 

https://ax.help.dynamics.com/en/wiki/delegates-for-migration/

https://blogs.msdn.microsoft.com/x/2011/08/02/how-to-use-x-delegates-in-dynamics-ax-2012/

https://en.wikipedia.org/wiki/Observer_pattern

 

11 Replies to “Using X++ Delegates in the new Dynamics AX (aka AX 7)”

  1. Unknown says:

    good information, with proper detail and example.

    Like

  2. kishorepvk says:

    The article about the delegation is nicely articulated with a live example. Nice work Rachit. Keep posting such articles on AX7. Please let me know, if I want to reach you how do I? My email id is kishorepvk@gmail.comThanksKishore

    Like

  3. Manish says:

    good one Rachit …keep it up.

    Like

  4. PAL says:

    Thank you Rachit, good detailed example.brBeat

    Like

  5. Arun Garg says:

    Good article with detailed example and really a very good work Rachit.

    Like

  6. Hey guys, I have a problem with my old software at my company. It's very slow and hard to manage, which makes it hard for us to develop. What to you think about getting ax dynamics? They seem to have a good offer for fair price. If you want to know more, click on the link and let me know what you think.

    Like

  7. Anonymous says:

    Hey there! I found coding the most difficult thing in Microsoft Dynamics AX, much harder than creating my website, but I would like to learn it. Thank you for the blog. I hope it will help me realize my goal. Cheers!

    Like

  8. Unknown says:

    Thank you much for sharing this with us, I'm waiting for your upcoming blogs on AX customization Your blog is nicely written and rich in content.

    Like

  9. Appreciate this post. Let me try it out.

    Like

  10. impotence says:

    Hi there! I simply want to give you a huge thumbs up for your excellent information you've got right here on this post. I'll be coming back to your website for more soon.

    Like

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