Question

An error has occurred while handling the request.

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Hi, I just started to work with Mendix and I'm practicing with a case I got from my company. In this case I'm building an app to calculate the money parents can get when their children are going to the day-care. For some reason I get the error below and I can't figure it out why it doesn't work. I tried locating the error with the debug tool and I thought I found it but that wasn't the case. I hope someone on the forum can help me out. Below you will find concerned microflow. Everything is in Dutch, if this is a problem I will translate so that everyone understands. If you have any questions let me know. Thanks in advance!

asked 2017-05-19

Luuk de Block

4 answers

Rom van Arendonk · Answer 1 · 2017-05-19

In this case, Mendix gives you a pretty good idea what you need to do if you read the error. You see two important things:

* Failed to evaluate expression at ... round($Aanvrager/WerkUrenMaand * 0,7)

* Left and right hand side of binary expression should not be empty

From this, it's easy to see that $Aanvrager/WerkUrenMaand is empty. This can be either because $Aanvrager is empty or because $Aanvrager/WerkUrenMaand is empty. Why it's empty, I can't tell: that is something that you need to figure out in your application.

Aswin van Braam · Answer 2 · 2017-05-19

Did you debug the microflow? That way you can easily find out why and when $Aanvrager is empty or when $Aanvrager/WerkUrenMaand is empty?

Luuk de Block · Answer 3 · 2017-05-19

Thanks for the reply!

I did read the error but I couldn't figure it out why it would be empty because if I want to calculate the "WerkUrenMaand" it works and I don't get this error. But when I don't want to calculate it but instead want to know the "Studie" this appears.

Luuk de Block · Answer 4 · 2017-05-19

Thanks everyone! I found the problem, like Luc said I thought empty (null) and 0 were the same thing. So I added a change object WerkUrenMaand to 0 and now it works!