I’ve never truly understood why we could explicitly commit a transaction, but we could only implicitly roll one back. There is a universe of difference between throwing an error (and ending the call stack), and rolling back (and continuing execution).
There was always a way to roll back and go on, sure. Wrap the entire thing in a if Codeunit.Run() block, throw an error as the last thing inside that codeunit, and there you go. Problem solved. Well, not quite.
Ancient wisdom goes that you cannot have more than one write transaction going on at the same time in a single session in NAV.
This is absolutely true, in and out.
Some features, like Activity Log, will leave you wanting to be able to write to the database outside of the normally running transaction.
Wouldn’t it just be beautiful if you could:
Well, in fact, you can do this.
Today at NAV TechDays 2015 in Antwerp, I attended a presentation by Nikola Kukrika, Ciprian Iordache, and Gary Winter, at which Ciprian presented a new design pattern based on a new feature in NAV 2016: Activity Log.
In a nutshell, this new feature, and thus the design pattern, aim at helping trace issues and facilitate troubleshooting by leaving information in the database about what was done, by whom, if it failed, and if it did, why.
All pretty and nice, but – as Ciprian pointed out – there is a bad aspect about it: when an error happens, and everything is rolled back – the activity entry is rolled back together with everything else. Nikola later explained how this could be solved through writing into temporary tables, but this either requires redesign by Microsoft or special coding techniques by you.
However, there is a bigger caveat than this. Non-persisting data in case of errors is a problem, but the bigger problem lies elsewhere. Let me explain that bigger problem here, and then give a silver-bullet solution to solve it all.
Did I CATCH your attention yet? At least I did TRY.
Now that I have completed my series on exception handling in C/AL, a very valid question pops up: why don’t we have try..catch syntactical constructs in C/AL, the way we have it in other programming languages?