Example Caldera Forms processor to add custom validation rules to a form. This is example code for a tutorial: https://calderawp.com/doc/creating-custom-validation-processor-caldera-forms/
If forking this repo to make your own field validator, at least search and replace "my_custom" with a unique slug, and change the function my_custom_cf_validator_is_valid to do the kind of validation you need for a field value.
- Copyright 2016 CalderaWP LLC and licensed under the terms of the GNU GPL version 2 or later.