How to deal with possible null values in Control conditions in Azure Logic App

Question

Hi,

I have a question about Control in Azure App Logic evaluating conditions where @(body) can in some cases be Null.

See the image for context.
The conditions in my Control do checks on responses from Azure functions.

Because I am implementing a finite state machine, sometimes, some of the Azure Functions do not execute.
The logic app fails because it tries to evaluate a condition on a @(body) that was Null.

The error I get is:
"
InvalidTemplate. Unable to process template language expressions for action 'Condition_-_Check_for_'Error'' at line '1'
and column '3141': 'The template language function 'contains' expects its first argument 'collection' to be a dictionary
(object), an array or a string. The provided value is of type 'Null'.'.
"

How can I deal with potential null values in Control?

Answer 1

Hello @BasvanZon-7304,

You can avoid this situation by checking whether the function is returning null. You can add a condition to check the function response.

Alternatively,

You could leave the comparison text as blank to compare it with null like below.

With the above condition in place you can filter off the null responses and work with the non-null responses.