How to validated multi-select field

[devingig]

I have a Nintex field based on a Site Column that is a Lookup.  To clarify, the site column is connected to a list at the root of the site collection and this list provides the lookup values for the field.

I enabled this Site Column for Multiple Selections, and then I changed the Appearance settings on the Nintex Form to show checkboxes.  All of this works fine.

Now, I want to have another field require a value if a certain value in that list is in the list of selected values.

I have seen multiple posts regarding how to validate if a check box is checked using isArray, and how to Array check box values,etc. and I have attempted the following validation rule on the ReportsTo field:

inArray(StatusReasons, 'Reports To Change') && isNullOrEmpty({Self})

Nothing is happening.  I suspect its because the source field is not actually an array because the source field is not a Choice field, but a Lookup field, but I am not certain.

Can you put the values of a multi select lookup field from SharePoint into an Array and evaluate as above?

[nps9]

Devin,

Could I get a little more info. When you say "I have a Nintex field based on a Site Column that is a Lookup" what type of Nintex field have you connected to the site look up column?

thanks

[devingig]

The field is a Lookup field in SharePoint, getting its data from another list,.  it is in a List Lookup field rendered as Option Buttons 

[nps9]

OK Devin,

I created a calculated value with the following expression:

contains(parseLookup(LookupColumn), 'Reports To Change')

Lookup column being the site column lookup.

So I get either true or false in the calculated value field but it is in string format not Boolean.

Then I created a validation rule with this expression: tbxReportsExists=='true' && ReqdTbx==""

tbxReportsExist being the calculated value field. ReqdTbx is the single line that is required if "Reports To Change" has been selected - regardless of if any of the other options have been selected.

No need for any kind of array.

[TomaszPoszytek]

‌ have you resolved your issue? Is any from the above answers helpful thus you could mark it as "correct"?

Regards,

Tomasz