Custom error message using CodeIgniter Form Validation

Right way of doing this is by passing a string format

$this->form_validation->set_message('is_unique', 'The %s is already taken');

So, then only we can able to get message like "This Username is already taken" or "This Email is already taken".

php forms codeigniter validation

This is how you set a message error ONLY for username:

$this->form_validation->set_rules('username','Username','is_unique',array('is_unique' => 'The %s is already taken'));

php forms codeigniter validation

This worked for me

$this->form_validation->set_message('is_unique', 'The username is already taken');

CodeHunter