如何在CodeIgniter中通过Ajax获取文件上传的表单验证错误

<form id="uploadForm" enctype="multipart/form-data">
    <input type="file" name="file">
    <input type="submit" value="Upload">
</form>

<script src="https://code.jquery.com/jquery-3.6.0.min.js"></script>
<script>
    $(document).ready(function() {
        $('#uploadForm').submit(function(e) {
            e.preventDefault(); // 阻止表单默认提交行为

            $.ajax({
                url: 'upload.php', // 后端处理文件上传的脚本
                type: 'POST',
                data: new FormData(this),
                processData: false,
                contentType: false,
                success: function(response) {
                    var errors = JSON.parse(response);
                    // 根据错误信息进行处理
                    if (errors.length > 0) {
                        // 显示错误信息
                        for (var i = 0; i < errors.length; i++) {
                            console.log(errors[i]);
                        }
                    } else {
                        // 文件上传成功
                        console.log('File uploaded successfully.');
                    }
                }
            });
        });
    });
</script>

<?php
defined('BASEPATH') OR exit('No direct script access allowed');

class Upload extends CI_Controller {
    public function index() {
        $this->load->library('form_validation');
        $this->form_validation->set_rules('file', 'File', 'required');

        if ($this->form_validation->run() == FALSE) {
            $errors = $this->form_validation->error_array();
            echo json_encode($errors);
        } else {
            // 文件上传成功的处理逻辑
            echo json_encode([]);
        }
    }
}