PDF未在Codeigniter中显示名称而不是id

CREATE TABLE `pdf_files` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `name` varchar(255) NOT NULL,
  `path` varchar(255) NOT NULL,
  PRIMARY KEY (`id`)
);

<form action="upload/process" method="post" enctype="multipart/form-data">
  <input type="file" name="pdf_file">
  <input type="submit" value="Upload">
</form>

class Upload extends CI_Controller {
  public function index() {
    $this->load->view('upload');
  }

  public function process() {
    $config['upload_path'] = './uploads/';
    $config['allowed_types'] = 'pdf';

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

    if (!$this->upload->do_upload('pdf_file')) {
      // 文件上传失败处理
    } else {
      $file_data = $this->upload->data();
      $pdf_name = $file_data['file_name'];
      $pdf_path = $file_data['full_path'];

      $this->load->model('pdf_model');
      $this->pdf_model->save_pdf($pdf_name, $pdf_path);

      // 文件上传成功处理
    }
  }
}

class Pdf_model extends CI_Model {
  public function save_pdf($name, $path) {
    $data = array(
      'name' => $name,
      'path' => $path
    );

    $this->db->insert('pdf_files', $data);
  }

  public function get_pdf_files() {
    return $this->db->get('pdf_files')->result_array();
  }
}

<?php foreach ($pdf_files as $pdf_file): ?>
  <a href="<?php echo $pdf_file['path']; ?>"><?php echo $pdf_file['name']; ?></a>
<?php endforeach; ?>

$route['default_controller'] = 'upload';