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'])

[khari14]

HI @Paulie78 , I tried to use this syntax for apply to each item but it did not work. Cna you guide me. Below is my flow

Syntax: 

if(equals(items('Apply_to_each_2')?['DISCHAREGE_x0020_DATE'], null), json('[]'), items('Apply_to_each_2')?['DISCHAREGE_x0020_DATE'])

Error I am facingSyntax of that item

[Paulie78]

The expression is doing what it is supposed to do, but you are trying to apply a date conversion to an empty array (so it will not work). It looks like you will probably need a condition at this point to skip this action if the array is empty (or make it supply a hard coded date to get past the error).

[khari14]

Yes, you are right but how? I tried both below with no luck

Sol 1:
coalesce(items('Apply_to_each_2')?['DISCHAREGE_x0020_DATE'],'')

Sol 2:
if(equals(items('Apply_to_each_2')?['DISCHAREGE_x0020_DATE'], null), json('[]'), items('Apply_to_each_2')?['DISCHAREGE_x0020_DATE'])

Same Error:

Evaluation of inputs for the expression action of kind 'ConvertTimeZone' failed: 'Required property 'baseTime' expects a value but got null. Path ''.'.

Regards

Hari

[Oatman2000]