获取公会 ID [Discord.py] [json]

Question

所以，当我的机器人离线并且有人在他们的服务器中添加它时，我在机器人再次启动后遇到了一个关键错误，因为在 json 文件中找不到 ID，所以我需要以某种方式解决这个问题，当机器人再次上线获取公会ID并放入json中时。有人告诉我做try except 的事情，但我不明白如何在机器人上线后获取公会 ID 并放入 json 这是代码，我觉得做起来很简单，但现在我真的不明白

    with open('prefixes.json' , 'r') as f:
        prefixes = json.load(f)

 
        return prefixes[str(message.guild.id)]

 
client = commands.Bot(command_prefix=get_prefix)



@client.event
async def on_guild_join(guild):
    with open('prefixes.json', 'r') as f:
        prefixes = json.load(f)

    prefixes[str(guild.id)] = 's!'

    with open('prefixes.json' , 'w') as f:
        json.dump(prefixes, f, indent = 4 )

@client.event
async def on_guild_remove(guild) :
    with open('prefixes.json' , 'r') as f:
        prefixes = json.load(f)

    prefixes.pop(str(guild.id))

    with open('prefixes.json' , 'w') as f:
        json.dump(prefixes, f, indent = 4 )```

Answer 1

try:
   # get prefix, and then return it
   with open('prefixes.json' , 'r') as f:
        prefixes = json.load(f)

 
        return prefixes[str(message.guild.id)]

except KeyError: # if the code above failed and raise KeyError code below will executed
   #insert the data to json, and the return the default prefix
   with open('prefixes.json', 'r') as f:
        prefixes = json.load(f)

    prefixes[str(message.guild.id)] = 's!'

    with open('prefixes.json' , 'w') as f:
        json.dump(prefixes, f, indent = 4 )
    return "s!" # or you can repeat the process of getting the prefix