Discord.py 封禁/解封Slash命令Cog报错求助

问题描述 #

开发带有moderation cog的Discord机器人，添加ban和unban命令后无法运行。已将commands.slash_command替换为client.tree.command，但报错提示回调函数ban.ban中的reason参数缺少类型注解。

报错信息 #

Traceback (most recent call last):
  File "C:\Users\playe\PycharmProjects\pythonProject3\cogs\ban.py", line 8, in <module>
    class ban(commands.Cog):
  File "C:\Users\playe\PycharmProjects\pythonProject3\cogs\ban.py", line 12, in ban
    @client.tree.command(name="ban", description="Bans a member from the server.")
     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\playe\PycharmProjects\pythonProject3\.venv\Lib\site-packages\discord\app_commands\tree.py", line 887, in decorator
    command = Command(
              ^^^^^^^^
  File "C:\Users\playe\PycharmProjects\pythonProject3\.venv\Lib\site-packages\discord\app_commands\commands.py", line 666, in __init__
    self._params: Dict[str, CommandParameter] = _extract_parameters_from_callback(callback, callback.__globals__)
                                                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\playe\PycharmProjects\pythonProject3\.venv\Lib\site-packages\discord\app_commands\commands.py", line 371, in _extract_parameters_from_callback
    raise TypeError(f'parameter {parameter.name!r} is missing a type annotation in callback {func.__qualname__!r}')
TypeError: parameter 'reason' is missing a type annotation in callback 'ban.ban'

Process finished with exit code 1

修复方案 #

• 给reason参数添加类型注解：Discord的app_commands（即tree.command）要求所有命令参数必须明确标注类型，包括可选参数。
• 移除cog内重复的Bot实例：cog不需要自己创建commands.Bot对象，应使用初始化时传入的self.bot。
• 替换命令注册的Bot实例：将cog中的client.tree.command改为self.bot.tree.command，确保使用主文件的Bot实例注册命令。
• 修正主文件的cog加载方式：主文件应通过load_extension加载cog，而非直接调用类。

修正后的代码 #

主命令文件 #

import discord
from discord.ext import commands

intents = discord.Intents.default()
intents.members = True  # 监听on_member_join需要此权限

client = commands.Bot(intents=intents)

@client.event
async def on_ready():
    print("Move Move Move")
    # 同步命令到Discord（全局同步，测试可用guild参数指定服务器）
    await client.tree.sync()

# 加载ban cog
client.load_extension("cogs.ban")

client.run("你的机器人Token")

Ban Cog文件 #

import discord
from discord.ext import commands

class Ban(commands.Cog):
    def __init__(self, bot):
        self.bot = bot

    @self.bot.tree.command(name="ban", description="将成员从服务器封禁")
    @commands.has_permissions(ban_members=True)
    async def ban(self, ctx, member: discord.Member, reason: str = None):
        """将成员从服务器封禁

        Args:
            ctx: 命令上下文
            member: 要封禁的成员
            reason: 封禁理由，可选，默认为None
        """
        if member == ctx.author:
            await ctx.respond("你不能封禁自己！")
            return

        if member == ctx.guild.owner:
            await ctx.respond("我不能封禁服务器所有者！")
            return

        if member.top_role >= ctx.author.top_role:
            await ctx.respond("你不能封禁角色等级比你高的成员！")
            return

        try:
            await member.ban(reason=reason)
            await ctx.respond(f"{member} 已被封禁！")
        except discord.HTTPException as e:
            await ctx.respond(f"封禁 {member} 失败。错误：{e}")

    @self.bot.tree.command(name="unban", description="解除成员的封禁")
    @commands.has_permissions(ban_members=True)
    async def unban(self, ctx, user: discord.User, *, reason: str = None):
        """解除成员的封禁

        Args:
            ctx: 命令上下文
            user: 要解除封禁的用户（可使用ID）
            reason: 解封理由，可选，默认为None
        """
        try:
            guild = ctx.guild
            banned_users = await guild.bans()
            target = [entry for entry in banned_users if entry.user == user]

            if not target:
                await ctx.respond(f"{user} 没有被封禁在此服务器！")
                return

            await guild.unban(user, reason=reason)
            await ctx.respond(f"{user} 已被解封！")
        except discord.HTTPException as e:
            await ctx.respond(f"解封 {user} 失败。错误：{e}")

def setup(bot):
    bot.add_cog(Ban(bot))

内容的提问来源于stack exchange，提问作者Rstarks