Custom error message using CodeIgniter Form 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'));

create a **form_validation.php** file and use this method:

"add_user_rule"   => [
    [
        "field" => "username",
        "label" => "Username",
        "rules" => "required|trim|is_unique[users.username]",
        "errors" => [
            'is_unique' => 'The %s is already taken.',
        ],
    ],
],

Thank You

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".