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设计报价应用程序。我正在使用BeautifulSoup从聪明的报价网站获得当天的报价。我会将它附加到文本文件中。在这里，如果已经添加了当天的引用，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 BeautifulSoup
import socket
import requests
import subprocess
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'})
    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()
    return
quotenotify()

输出文件：

Mar 29  Where there is a great love, there are always wishes. - Willa Cather
Mar 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

如@DirtyBit所述，您应首先以读取模式打开文件，然后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上，然后仅在变量不在文本文件中时附加到文件。

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()