Null error when selecting from empty array

[BrandonQuinn]

I have several mulitple choice questions in a Microsoft form. Multiple answers are allowed for the questions, and so after some Googling I am using Compose to get the answer array and then Select to select the items within that array to display when I automate the form responses into a SharePoint list. However, the new form I'm using branches off, and so some of the multiple choice fields are skipped and left blank. I then get the error "The 'from' property value in the 'select' action inputs is of type 'Null'. The value must be an array.". 

Has anyone come across this error before or knows another one to handle it?

[Paulie78 · Accepted solution]

Yes, you can handle this with an expression like this:

if(equals(outputs('somearray'), null), json('[]'), outputs('somearray'))

You would replace:

outputs('somearray') with whatever you array is. This expression is basically saying, if the array is equal to null, then use json('[]') as the output instead. which will produce a valid, but empty array.

[BrandonQuinn]

Thank you very much! This worked for all my branched multiple choice questions.

[BrandonQuinn]

Thank you very much! This worked for all my branched multiple choise questions.

[Anonymous]

Where would I write this expression. I seem to be having the same problem

[Oatman2000]

Hi Paulie, 
I am having the same issue where the form logic can be skipped based on questions and it's causing my error. 
"The 'from' property value in the 'select' action inputs is of type 'Null'. The value must be an array."

Where do I key this into my flow? 

if(equals(outputs('somearray'), null), json('[]'), outputs('somearray'))

Currently this is mine:
 json(outputs('Get_response_details')?['body/re166e862ac2e43b5a854017b21fe7637'])

Tried this and it still failed:

if(equals(outputs('Get_response_details'), null), json('[]'), outputs('Get_response_details')?['body/re166e862ac2e43b5a854017b21fe7637'])