I have tried to follow a couple of posts about this, but either they are incomplete or don't work for me.
Here's my issue:
I am allowing a user to register and collect their date of birth in 3 separate fields.
I need to check the date entered to make sure they are over 18, and I would like to generate a standard validation error if not. So this is not a rule I can attach to one field as it's 3 fields, that I will need to make into a timestamp and validate.
Can anyone help?