检查文本文件的内容，如果不存在则添加内容

Question

我是python的新手。我正在使用 python 设计一个报价应用程序。我使用 BeautifulSoup 从聪明的报价网站获取当天的报价。我会将它附加到文本文件中。在这里，如果当天的报价已经添加，当我再次执行程序时，它应该跳过它。如何使它成为可能这是代码：from bs4 import BeautifulSoupimport socketimport requestsimport subprocessimport datetimedef quotenotify():    timestamp = datetime.datetime.now().strftime("%b %d")    res = requests.get('https://www.brainyquote.com/quote_of_the_day')    soup = BeautifulSoup(res.text, 'lxml')    image_quote = soup.find('img', {'class': 'p-qotd bqPhotoDefault bqPhotoDefaultFw img-responsive delayedPhotoLoad'})    quoteday=image_quote['alt']    text_file = open("quotes.log", "a+")    text_file.write("%s"%timestamp+"\t"+"%s"% quoteday)    text_file.write("\n")    text_file.close()    returnquotenotify()在文件中输出：Mar 29  Where there is a great love, there are always wishes. - Willa CatherMar 29  Where there is great love, there are always wishes. - Willa Cather

Answer 1

继续评论：

from bs4 import BeautifulSoup

import requests

import datetime

def quotenotify():

    timestamp = datetime.datetime.now().strftime("%b %d")

    res = requests.get('https://www.brainyquote.com/quote_of_the_day')

    soup = BeautifulSoup(res.text, 'lxml')

    image_quote = soup.find('img', {'class': 'p-qotd bqPhotoDefault bqPhotoDefaultFw img-responsive delayedPhotoLoad'})['alt']

    with open("quotes.log", "w+") as f:

        if image_quote not in f.read():

            f.write("%s"%timestamp+"\t"+"%s"% image_quote + "\n")

quotenotify()

编辑：

由于使用该模式w+会截断文件，我建议使用 pathlib：

from bs4 import BeautifulSoup

import requests

import datetime

from pathlib import Path

def quotenotify():

    timestamp = datetime.datetime.now().strftime("%b %d")

    res = requests.get('https://www.brainyquote.com/quote_of_the_day')

    soup = BeautifulSoup(res.text, 'lxml')

    image_quote = timestamp + "\t" + soup.find('img', {'class': 'p-qotd bqPhotoDefault bqPhotoDefaultFw img-responsive delayedPhotoLoad'})['alt']

    with open("quotes3.log", "a+") as f:

        contents = [Path("quotes3.log").read_text()]

        print(contents)

        print(image_quote)

        if image_quote not in contents:

            f.write("%s" % timestamp + "\t" + "%s" % image_quote + "\n")

quotenotify()

Answer 2

您应该首先以读取模式打开文件并将内容加载到变量中。

您可以在下面的示例中看到，我将内容加载到变量中，然后仅当变量不在文本文件中时才附加到文件中。

text_file = open('test-file.txt', 'r+')

read_the_file = text_file.read()

text_file.close()

text_file = open('test-file.txt', 'a+')

new_string = 'Smack Alpha learns python'

if new_string not in read_the_file:

    text_file.write(new_string + '\n')

text_file.close()