export to json format inference model by default

paddlex/utils/flags.py

@@ -48,7 +48,7 @@ DEBUG = get_flag_from_env_var("PADDLE_PDX_DEBUG", False)
 DRY_RUN = get_flag_from_env_var("PADDLE_PDX_DRY_RUN", False)
 CHECK_OPTS = get_flag_from_env_var("PADDLE_PDX_CHECK_OPTS", False)
 EAGER_INITIALIZATION = get_flag_from_env_var("PADDLE_PDX_EAGER_INIT", True)
-FLAGS_json_format_model = get_flag_from_env_var("FLAGS_json_format_model", None)
+FLAGS_json_format_model = get_flag_from_env_var("FLAGS_json_format_model", True)
 USE_PIR_TRT = get_flag_from_env_var("PADDLE_PDX_USE_PIR_TRT", False)
 DISABLE_DEV_MODEL_WL = get_flag_from_env_var("PADDLE_PDX_DISABLE_DEV_MODEL_WL", False)
 DISABLE_CINN_MODEL_WL = get_flag_from_env_var("PADDLE_PDX_DISABLE_CINN_MODEL_WL", False)