How to validate a field only if an option is selected - RAILS 5

Question

could one kindly advise me how i validate a field only if an option is selected

• so i have the selector that has the options: parent & service provider
• when service provider is selected the hidden selector services is displayed
• i want to validate the presences of services only when service provider is selected (not when parent is selected) as per image

will it be written something like the below: validates_presence_of :category_service_id, presence: true, if: :category_segment_id?, message: "can't be blank "

could one kindly advise me on this

Answer 1

You're very close. What you need to do is make a conditional validation (More about it in the official guides ).

You'd need to do the following:

validates_presence_of :category_service_id, if: :service_provider?

# Marking the validation check method as private is optional, but recommended
private

def service_provider?
  <Your code to check if segment is service_provider comes here>
end

message is not required since the default error message would be can't be blank .

I would highly recommend reading the doc mentioned in the link above for a better understanding of validations.

NOTE: service_provider? method is not required in case you're using enums to decide between service_provider and parent since enums define option? methods by default.