How to disable multi select custom field when specific value is added

[Giannis Michailidis]

I have created a custom field that allows multiple values.

I would like to know if there is a way to disable multiple values and and allow only one through validator.

e.g. when I select a specific value (e.g. "Complaints") then the field should not allow to input any other values.

[Fazila Ashraf]

Hi @Giannis Michailidis 

Welcome to community!

For the given use case, the best approach is to set the value to the field through automation or a post function.

With an automation, you can set the value to the field , on conditions that the transition happens and the other field value is complaints.

[Giannis Michailidis]

i would like to set up a message to the user through validator (if the value is the desired one) and not a post function or automation