没有足够的值来解包（预期 3，得到 1）

Question

我遇到了以下问题，我不知道如何解决它。 请帮忙，如果您也能解释一下您是如何做到的，那就太好了。

 import csv, smtplib, ssl
 
 message = """Subject: Your grade
 
 Hi {name}, your grade is {grade}"""
 from_address = "michael@gmail.com"
 password = input("Type your password and press enter: ")
 
 context = ssl.create_default_context()
 with smtplib.SMTP_SSL("smtp.gmail.com", 465, context=context) as server:
     server.login(from_address, password)
     with open("contacts_file.csv") as file:
         reader = csv.reader(file)
         next(reader)  # Skip header row
         for name, email, grade in reader:
             server.sendmail(
                 from_address,
                 email,
                 message.format(name=name,grade=grade),
             )

错误

---

ValueError                                Traceback (most recent call last)
/var/folders/q8/qn3d11d90fbbz0j6kllhpn9h0000gn/T/ipykernel_34629/2824055323.py in <module>
     13         reader = csv.reader(file)
     14         next(reader)  # Skip header row
---> 15         for name, email, grade in reader:
     16             server.sendmail(
     17                 from_address,

ValueError: not enough values to unpack (expected 3, got 1)

Answer 1

您的主要问题是您的文件是用分号分隔的，并且 CSV 阅读器希望文件用逗号分隔。

这是你现在拥有的：

with open('contacts_file.csv') as file:
    reader = csv.reader(file)
    next(reader)  # Skip header row
    for row in reader:
        print(row)

看起来像这样：

['michael;y@gmail.com;2']
['zas;s@gmail.com;32']
['dasdas;btnike888@vireonidae.com;32']
['dasdas;ym2000@gmail.com;312']

您的行是一个字符串的列表，这会导致您的“解包错误”：您希望每一行（列表）包含三个项目，但现在只有一个项目：整行。

指定分隔符：

reader = csv.reader(file, delimiter=';')

你会得到：

['michael', 'y@gmail.com', '2']
['zas', 's@gmail.com', '32']
['dasdas', 'btnike888@vireonidae.com', '32']
['dasdas', 'ym2000@gmail.com', '312']

现在您可以解压缩每一行：

for row in reader:
    name, email, grade = row
    ...

我建议阅读row整个事情，然后拆包row 。 更容易检查正确性和调试：

for row in reader:
    assert len(row) == 3, f'Expected 3 columns but only have {len(row)}: {row}'
    name, email, grade = row

对于您的原始设置，您会收到一个有用的错误，例如：

AssertionError: Expected 3 columns but only have 1: ['michael;y@gmail.com;2']