如果在 python 中找不到文件，有没有办法抛出异常？

Question

我正在制作一个程序，以便可以轻松地将电子邮件发送给一组人，每个收件人都有一个唯一的文件。该程序以 .csv 文件的形式读取列表，其中包含每个收件人的姓氏、名字、电子邮件地址和各自的附件，使用模板自定义带有收件人姓名的每封电子邮件，并附上他们的文件。

代码如下。我为主题行和电子邮件地址使用了占位符，并隐藏了电子邮件的实际文本，但您应该能够理解。 email_data 变量是包含收件人信息的 .csv 文件最初加载到的位置。

import csv
import datetime
import sys

import smtplib
import yagmail

import tkinter as tk
from tkinter import filedialog
from tkinter import simpledialog

root = tk.Tk()
root.withdraw()

password = simpledialog.askstring("Password", "Enter password:", show='*')

current_date = datetime.datetime.now()

subject_line = f'xyz {current_date.strftime("%B")} {current_date.year} xyz File'

LNAMES = []
FNAMES = []
EMAILS = []
FILES = []

yag = yagmail.SMTP('xyz@xyx.com', password)

email_data = filedialog.askopenfilename(filetypes=[('.csv', '.csv')],
                                        title='Select the Email Data file')


def send_email():

    with open(email_data) as csv_file:
        csv_reader = csv.reader(csv_file, delimiter=',')
        line_count = 0

        for row in csv_reader:
            last_name = row[0]
            first_name = row[1]
            email = row[2]
            file = row[3]

            LNAMES.append(last_name)
            FNAMES.append(first_name)
            EMAILS.append(email)
            FILES.append(file)

            line_count += 1

    try:
        for first_name, last_name, email, file in zip(FNAMES, LNAMES, EMAILS, FILES):
            txt = '...'
            yag.send(to=email,
                     subject=subject_line,
                     contents=[txt, file])

            print("Email(s) sent successfully")
            input("Press Enter to exit")
            sys.exit(1)

    except smtplib.SMTPAuthenticationError:
        print("Incorrect Email password entered")
        input("Press Enter to exit")
        sys.exit(1)


send_email()

我运行遇到的问题是，如果列出的文件不在工作目录中，则发送电子邮件时会在电子邮件底部附上一段文字，内容类似于 "file.xlsx" 而不是实际的附件。如果找不到文件，是否可以抛出异常，这样电子邮件就不会只是发送没有真正的附件？

Answer 1

您可以编写自己的异常：

class EmailAttachmentNotFoundException(Exception):
     pass

然后在附加文件的代码中：（为清楚起见删除了其余代码）：

def send_email():

with open(email_data) as csv_file:
    csv_reader = csv.reader(csv_file, delimiter=',')
    line_count = 0

    for row in csv_reader:
        last_name = row[0]
        first_name = row[1]
        email = row[2]
        file = row[3]
        if not os.isfile(file):
            raise EmailAttachmentNotFoundException('Could not find file {} Aborting!!!!'.format(file))

        LNAMES.append(last_name)
        FNAMES.append(first_name)
        EMAILS.append(email)
        FILES.append(file)

        line_count += 1

如果你想在线捕获它：

try:
    send_email()
except EmailAttachmentNotFoundException as e:
    # Modify the way the exception is raised and how it is captured, but this is the most basic way of getting what is inside 
    print(str(e))

这会打印：

'Could not find file myfile.txt Aborting!!!!'

Answer 2

或者，如果您不想例外，您可以跳过该行：

with open(email_data) as csv_file:
    csv_reader = csv.reader(csv_file, delimiter=',')
    line_count = 0

    for row in csv_reader:
        last_name = row[0]
        first_name = row[1]
        email = row[2]
        file = row[3]
        if not os.isfile(file):
            continue             # <-----

        LNAMES.append(last_name)
        FNAMES.append(first_name)
        EMAILS.append(email)
        FILES.append(file)

        line_count += 1

continue 将跳过其余代码并返回到 for 循环。如果您想查看不存在的反馈，您可以在 continue 正上方添加打印语句。

Answer 3

使用

import os

if os.path.exists(file_path):
    do_someting()
else:
    raise SOME_ERROR()

查看文件是否存在。

如果在 python 中找不到文件，有没有办法抛出异常？

Is there a way to throw an exception if a file is not found in python?

python

csv

email

smtplib

yagmail

这会打印：