Discord机器人/level命令报错：'NoneType' object has no attribute 'author'

问题描述 #

开发Discord机器人等级系统时，实现/level命令用于显示指定用户等级；未指定用户时默认显示命令发起者等级。编写代码if member is None: member = interaction.message.author时触发报错：'Nonetype' object has no attribute 'author'。

尝试过用ctx替代interaction，测试ctx.author、ctx.message.author，也试过interaction.author，修改参数名为user，但问题未解决。

命令代码 #

# Level Command | !level {member} | Shows you your current level or the level of another member.
@bot.tree.command(name="level", description="Shows you your current level or the level of another member.")
@app_commands.describe(member="The member who's level you want to see.")
async def level(interaction: discord.Interaction, member: discord.Member = None):
    if member is None:
        member = interaction.message.author
    async with bot.db.cursor() as cursor:
        await cursor.execute("SELECT level FROM levels WHERE user = ? AND guild = ?", (member.id, interaction.guild.id,))
        level = await cursor.fetchone()
        await cursor.execute("SELECT xp FROM levels WHERE user = ? AND guild = ?", (member.id, interaction.guild.id,))
        xp = await cursor.fetchone()
    
    if not xp or not level:
        await cursor.execute("INSERT INTO levels (levels, xp, user, guild) VALUES (?, ?, ?, ?)", (0, 0, member.id, interaction.guild.id,))

    try:
        xp = xp[0]
        level = level [0]
    except TypeError:
        xp = 0
        level = 0
    
    user_data = {
        "xp": xp,
        "level": level,
        "next_level_up": 100,
        "percentage": xp
    }

    background = Editor(Canvas((900, 300), color="#191919"))
    profile_picture = await load_image_async(str(member.avatar.url))
    profile = Editor(profile_picture).resize((150, 150)).circle_image()

    poppins = Font.poppins(size=40)
    poppins_small = Font.poppins(size=40)

    card_right_shape = [(600, 0), (750, 300), (900, 300), (900, 0)]

    background.polygon(card_right_shape, color="#FFFFFF")
    background.paste(profile, (30, 30))

    background.rectangle((30, 220), width=650, height=40, color="#FFFFFF")
    background.bar((30, 220), max_width=650, height=40, percentage=user_data["percentage"], color="#FF0000", radius=20)
    background.text((200, 40), user_data["name"], font=poppins, color="#FFFFFF")

    background.rectangle((200, 100), width=350, height=2, fill="#FFFFFF")
    background.text((200, 130), f"Level - {user_data['level']} | XP - {user_data['xp']}/{user_data['next_level_up']}", font=poppins_small, color="#FFFFFF")

    file = discord.File(fp=background.image_bytes, filename="levelcard.png")
    await interaction.response.send_message(file=file)

报错信息 #

Traceback (most recent call last):
    bot.py line 83, in level
    member = interaction.message.author
AttributeError: 'NoneType' object has no attribute 'author'

解决方案 #

核心问题 #

使用的是Discord.py的斜杠命令（slash command），这类命令的interaction对象不存在message属性（interaction.message为None），因为斜杠命令并非基于消息触发，和传统前缀命令的逻辑不同。

具体修复步骤 #

1. 修正发起者获取方式
   将member = interaction.message.author替换为member = interaction.user，斜杠命令中interaction.user直接指向命令发起者，且在服务器内使用时为discord.Member类型。

2. 修复数据库字段名不匹配
   插入语句中字段名levels与查询的level不一致，修改为：

await cursor.execute("INSERT INTO levels (level, xp, user, guild) VALUES (?, ?, ?, ?)", (0, 0, member.id, interaction.guild.id,))

3. 补充user_data缺失的name字段
   代码中调用user_data["name"]但未定义，添加该字段：

user_data = {
    "name": member.display_name,
    "xp": xp,
    "level": level,
    "next_level_up": 100,
    "percentage": (xp / 100) * 100 if 100 > 0 else 0  # 修正百分比计算逻辑
}

4. 添加数据库提交操作
   执行INSERT后未提交，数据不会写入数据库，添加提交语句：

if not xp or not level:
    await cursor.execute("INSERT INTO levels (level, xp, user, guild) VALUES (?, ?, ?, ?)", (0, 0, member.id, interaction.guild.id,))
    await bot.db.commit()

修复后核心代码片段 #

@bot.tree.command(name="level", description="Shows you your current level or the level of another member.")
@app_commands.describe(member="The member who's level you want to see.")
async def level(interaction: discord.Interaction, member: discord.Member = None):
    if member is None:
        member = interaction.user  # 修复发起者获取
    async with bot.db.cursor() as cursor:
        await cursor.execute("SELECT level FROM levels WHERE user = ? AND guild = ?", (member.id, interaction.guild.id,))
        level = await cursor.fetchone()
        await cursor.execute("SELECT xp FROM levels WHERE user = ? AND guild = ?", (member.id, interaction.guild.id,))
        xp = await cursor.fetchone()
    
    if not xp or not level:
        await cursor.execute("INSERT INTO levels (level, xp, user, guild) VALUES (?, ?, ?, ?)", (0, 0, member.id, interaction.guild.id,))
        await bot.db.commit()  # 提交数据库修改

    try:
        xp = xp[0]
        level = level[0]
    except TypeError:
        xp = 0
        level = 0
    
    user_data = {
        "name": member.display_name,  # 补充name字段
        "xp": xp,
        "level": level,
        "next_level_up": 100,
        "percentage": (xp / 100) * 100 if 100 > 0 else 0  # 修正百分比
    }

    # 后续图片编辑与发送代码保持不变

内容的提问来源于stack exchange，提问作者Taylordood