将文件从HttpClient Angular提交到CodeIgniter -Rest API 3

import { HttpClient } from '@angular/common/http';

...

constructor(private http: HttpClient) {}

submitFile(file: File) {
  const formData = new FormData();
  formData.append('file', file);

  return this.http.post('http://example.com/api/upload', formData);
}

<?php
require APPPATH.'/libraries/REST_Controller.php';

class FileUpload extends REST_Controller {
  public function upload_post() {
    $config['upload_path'] = './uploads/';
    $config['allowed_types'] = 'gif|jpg|png';

    $this->load->library('upload', $config);

    if ($this->upload->do_upload('file')) {
      $data = $this->upload->data();
      $file_url = base_url('uploads/'.$data['file_name']);
      $this->response(['status' => 'success', 'file_url' => $file_url], REST_Controller::HTTP_OK);
    } else {
      $this->response(['status' => 'error', 'error_message' => $this->upload->display_errors()], REST_Controller::HTTP_BAD_REQUEST);
    }
  }
}

$route['api/upload'] = 'fileupload/upload';