How do I validate a single form field in CodeIgniter?
<p>I have a form that has validation rules that are set in a config file.  I want to validate this form field using AJAX so that when focus leaves a certain form field, that field is checked by CI's form validation class.  I have a jQuery AJAX script that calls one of my controllers which I would like to have validate the form field.  using the form_validation->run('group') method won't work for this because it checks everything in the form and will always return false.  How can I validate a single form field in CodeIgniter?</p>