discord.py使用cogs实现Snipe撤回消息查看功能运行异常求助

核心问题点 #

• on_message_delete事件未添加@commands.Cog.listener()装饰器，框架不会触发该回调，删除消息的存储逻辑从未执行
• 存储删除消息的字典被定义为on_message_delete的局部变量，每次事件执行都会重置为空，且执行结束后变量直接销毁，数据无法留存供命令读取
• snipe命令错误尝试从ctx对象读取不存在的messagecontent属性，必然抛出异常进入错误分支

修复后完整代码 #

import discord
from discord.ext import commands

class Snipe(commands.Cog):

    def __init__(self, client):
        self.client = client
        # 初始化类实例属性存储删除消息数据，全局生效
        self.snipe_author = {}
        self.snipe_content = {}

    @commands.Cog.listener()
    async def on_ready(self):
        print("Snipe is now enabled")
    
    # 添加事件监听装饰器
    @commands.Cog.listener()
    async def on_message_delete(self, message):
        # 数据存入实例属性，不会被销毁
        self.snipe_author[message.channel.id] = message.author
        self.snipe_content[message.channel.id] = message.content

    @commands.command()
    async def snipe(self, ctx):
        channel = ctx.channel
        try:
            # 从实例属性读取存储的消息数据
            author = self.snipe_author[channel.id]
            content = self.snipe_content[channel.id]
            em = discord.Embed(description = f"{author.mention} said:\n{content}", color = 0x00c230)
            em.set_author(name = f"Last deleted message in #{ctx.channel.name}")
            em.set_thumbnail(url="https://cdn.discordapp.com/avatars/352793093105254402/8a2018de21ad29973696bfbf92fc31cd.png?size=4096")
            em.set_footer(text = f"Snipe requested by {ctx.message.author}")
            await ctx.send(embed = em)
        except KeyError:
            embed = discord.Embed(colour = 0x00c230)
            embed.set_author(name=f"There are no deleted messages in #{ctx.channel.name}!")
            embed.set_thumbnail(url="https://cdn.discordapp.com/avatars/352793093105254402/8a2018de21ad29973696bfbf92fc31cd.png?size=4096")
            embed.set_footer(text=f"Snipe requested by {ctx.message.author}")
            await ctx.send(embed=embed)

def setup(client):
    client.add_cog(Snipe(client))

附加优化说明 #

• 把原来的裸except改为捕获KeyError，避免吞掉其他未知异常方便后续排查
• 消息内容展示补充了发送者@提醒，信息更完整

内容的提问来源于stack exchange，提问作者53x2