form validation in codeigniter 4.1 code example

Example 1: codeigniter load form_validation

<?php

class Form extends CI_Controller {

        public function index()
        {
                $this->load->helper(array('form', 'url'));

                $this->load->library('form_validation');

                if ($this->form_validation->run() == FALSE)
                {
                        $this->load->view('myform');
                }
                else
                {
                        $this->load->view('formsuccess');
                }
        }
}

Example 2: form validation input inside api codeigniter

$this->form_validation->set_rules('user_api_key', 'User Api Id', 'trim|required');

if ($this->form_validation->run() == FALSE) {
  $data = strip_tags($this->form_validation->error_string());
  return $this->json_out($data, 0, $code = 'form_validation_error', $msg = 'Some Fields are required');
}