PTB父子ConversationHandler优先级问题：如何让子状态优先处理更新？

在使用Python Telegram Bot（PTB）的父子嵌套ConversationHandler时，遇到了状态优先级问题：子状态无法优先处理更新，父状态的处理器会先被触发。

单嵌套场景代码 #

...
child_conv_handler = ConversationHandler(
    entry_points=[CommandHandler("start_child", start_child_func)],
    states={
        CHILD_STATE:  [
            CommandHandler("search", search),
            CommandHandler("add", add),
            CommandHandler("exit", exit),
        ],
    },
    fallbacks=[MessageHandler(filters.TEXT, fallback_message),],
)


parent_conv_handler = ConversationHandler(
    entry_points=[CommandHandler("start_parent", start_parent_func)],
    states={
        PARENT_STATE:  [
            CommandHandler("stats", stats),
            child_conv_handler,
        ],
    },
    fallbacks=[CommandHandler("stop", stop)],
)

application.add_handler(parent_conv_handler)

application.run_polling(allowed_updates=Update.ALL_TYPES)

操作流程与问题表现 #

• 发送/start_parent启动父ConversationHandler；
• start_parent_func回调返回对话状态PARENT_STATE；
• 发送/start_child启动子ConversationHandler；
• start_child_func回调返回对话状态CHILD_STATE；
• 发送/stats命令时，触发的是父级PARENT_STATE下的CommandHandler("stats", stats)，而非子状态的对应处理器。

此时机器人同时处于PARENT_STATE和CHILD_STATE，但父状态优先级更高。单个子Handler的情况可以通过调整处理器顺序解决，但多子Handler场景下这个方法不适用：

多子嵌套场景代码 #

...

child_conv_handler1 = ConversationHandler(
    entry_points=[CommandHandler("start_child1", start_child_func1)],
    states={
        CHILD_STATE1:  [
            CommandHandler("stats", child_stats1),
        ],
    },
    fallbacks=[MessageHandler(filters.TEXT, fallback_message),],
)
     
child_conv_handler2 = ConversationHandler(
    entry_points=[CommandHandler("start_child2", start_child_func2)],
    states={
        CHILD_STATE2:  [
            CommandHandler("stats", child_stats2),
        ],
    },
    fallbacks=[MessageHandler(filters.TEXT, fallback_message),],
)


parent_conv_handler = ConversationHandler(
    entry_points=[CommandHandler("start_parent", start_parent_func)],
    states={
        PARENT_STATE:  [
            CommandHandler("stats", parent_stats),
            child_conv_handler1,
            child_conv_handler2
        ],
    },
    fallbacks=[CommandHandler("stop", stop)],
)

application.add_handler(parent_conv_handler)

application.run_polling(allowed_updates=Update.ALL_TYPES)

需求 #

如何让子状态成为主状态，或者在启动子Handler时将父Handler置于“停滞状态”？

内容的提问来源于stack exchange，提问作者EKong