Hi @pikachu而不是这样做-

Hi @pikachu instead of doing this -

$this->form_validation->set_rules('username', 'Email', 'trim|required|valid_email|callback_IsEmail_exist');

使用管道元素将其分成单独的参数，例如-

use the piped elements separate into individual parameters like -

$this->form_validation->set_rules('username', 'Email', 'required', 'callback_IsEmail_exist');

这可能会对您有所帮助。

this may be help you.