def dl_plan(pid):

     """

     下载测试计划关联的测试文件，分单个和多个文件情况（多个文件打包成zip下载）。

     1. 计划只有一个文件则直接下载.xlsx文件

     2. 计划有多个文件，则打包成zip通过BytesIO直接写入到内存中，不在本地生成.zip文件。

     :param pid

     :return:

     """

     dirpath = Config.FILE_UPLOAD_DIR

     tp = TestPlan.objects.get_or_404(id=pid)

     fp_test_files = tp.test_files

     file_list = fp_test_files.split(",")

     dl_name = '{}.zip'.format(tp.planname)

     if len(file_list) == 1:

         return send_from_directory(dirpath, fp_test_files, as_attachment=True)

     else:

         memory_file = BytesIO()

         with zipfile.ZipFile(memory_file, "w", zipfile.ZIP_DEFLATED) as zf:

             for _file in file_list:

                 with open(os.path.join(dirpath, _file), 'rb') as fp:

                     zf.writestr(_file, fp.read())

         memory_file.seek(0)

         return send_file(memory_file, attachment_filename=dl_name, as_attachment=True)