错误 - TypeError: 'NoneType' 对象不可下标

Question

在下面的 if else 语句中出现错误。如果 df2 中的记录数 > 5，则希望通过电子邮件发送，否则退出。有任何想法吗？谢谢！！

df2 = df.select("pull_date","promo_amt") \
.groupby("pull_date") \
.agg(count("promo_amt").alias("Tots"),sum("promo_amt").alias("Sums")) \
.filter(df["pull_date"] == current_date()).show() 

if df2['Tots'] > 5:

    import smtplib, ssl
    port = xxx 
    smtp_server = "smtpserver"
    sender_email = "xxx#xxx.com"
    receiver_email = "xxx#xxx.com"
    password = "xxxxx"
    message = """\
    Subject: Test
    Test message please ignore."""
    context = ssl.create_default_context()
    with smtplib.SMTP_SSL(smtp_server, port, context=context) as server:
    server.login(sender_email, password)
    server.sendmail(sender_email, receiver_email, message)
else:
    exit()