Python追加写入txt文件失败回退主菜单问题排查

问题现象 #

开发库存管理程序时，需实现用户输入商品名称、预估价格、库存数量后，将对应商品信息保存到txt文本文件的功能。当前异常表现为：程序执行打开txt文件写入内容的操作时，无实际数据写入文件，程序直接循环回退到主菜单函数，仅打印Please choose a valid action!错误提示，相关代码如下：

def user_interface_menu():
    while True:
        try:
            print("""
--------------------------------------------------------------
                            Menu
--------------------------------------------------------------
1 - Show one item information
2 - Show all stock information
3 - Add item
4 - Update item
5 - Remove item
6 - Save and exit
7 - Exit without save""")

            user_action = int(input("Action - "))

            if user_action not in (1, 2, 3, 4, 5, 6, 7):
                print("Please choose a valid action!")
            elif user_action == 1:
                one_item_information()

            elif user_action == 2:
                all_stock_information()

            elif user_action == 3:
                add_item()

            elif user_action == 4:
                update_item()

            elif user_action == 5:
                remove_item()

            elif user_action == 6:
                save_exit()

            elif user_action == 7:
                exit_no_save()

        except:
            print("Please choose a valid action!")




def add_item():
    try:
        stock_name = input("""
    Please state the name of the product. - """)
        stock_name = str(stock_name)

        price_estimate = input("""
    Please state the estimated price of the product. - """)
        price_estimate = float(price_estimate)

        stock_quantity = input("""
    Please state the quantity of the product. - """)
        stock_quantity = int(stock_quantity)

        print("")
        print("New item Added! - ", end="")
        print(stock_name, price_estimate, stock_quantity)

        with open("store_stock.txt", "a") as f:
            user_addition = input("")
            f.write(stock_name, price_estimate, stock_quantity)
            f.write("\n")
    except:
        print("incorrect")

故障原因 #

• 存在无意义的阻塞输入语句：add_item()函数打开文件后，第一行是无任何提示的user_addition = input("")，程序运行到这里会暂停等待用户输入，但控制台没有任何提示，用户很容易误以为回到了菜单选择步骤，直接输入菜单序号。
• write()方法调用参数错误：Python文件对象的write()方法仅接受1个字符串类型参数，代码中同时传入了字符串、浮点数、整数三个不同类型的参数，会直接触发TypeError，导致写入操作失败。
• 裸异常捕获吞掉了具体错误：两个函数都用了不指定异常类型的裸except，会把所有运行时错误全部拦截，既不打印具体错误信息，也不做针对性处理，导致错误被掩盖，最终表现为跳回主菜单打印无效操作提示。

修复方案 #

1. 删除add_item()中无意义的user_addition = input("")语句，去掉不必要的输入阻塞。
2. 修正文件写入逻辑，先将商品名称、价格、库存拼接为格式统一的字符串（非字符串类型先做类型转换），再传入write()方法，建议打开文件时指定encoding="utf-8"避免中文乱码。
3. 替换裸except为具体异常捕获，避免吞掉非预期错误，方便后续排查问题。

修复后的核心代码参考：

def user_interface_menu():
    while True:
        try:
            print("""
--------------------------------------------------------------
                            Menu
--------------------------------------------------------------
1 - Show one item information
2 - Show all stock information
3 - Add item
4 - Update item
5 - Remove item
6 - Save and exit
7 - Exit without save""")

            user_action = int(input("Action - "))

            if user_action not in (1, 2, 3, 4, 5, 6, 7):
                print("Please choose a valid action!")
            elif user_action == 1:
                one_item_information()
            elif user_action == 2:
                all_stock_information()
            elif user_action == 3:
                add_item()
            elif user_action == 4:
                update_item()
            elif user_action == 5:
                remove_item()
            elif user_action == 6:
                save_exit()
            elif user_action == 7:
                exit_no_save()

        except ValueError:
            # 仅捕获菜单输入类型错误，不吞其他异常
            print("Please choose a valid action!")


def add_item():
    try:
        stock_name = input("""
    Please state the name of the product. - """).strip()
        price_estimate = float(input("""
    Please state the estimated price of the product. - """).strip())
        stock_quantity = int(input("""
    Please state the quantity of the product. - """).strip())

        print("")
        print("New item Added! - ", end="")
        print(stock_name, price_estimate, stock_quantity)

        with open("store_stock.txt", "a", encoding="utf-8") as f:
            # 拼接为逗号分隔的字符串，可根据需要调整分隔符
            f.write(f"{stock_name},{price_estimate},{stock_quantity}\n")
    except ValueError:
        print("输入格式错误：价格请输入数字，库存请输入整数")
    except Exception as e:
        print(f"商品添加失败：{str(e)}")

内容的提问来源于stack exchange，提问作者Sprinklerasian