检查csv Python中是否存在行

Question

我是Python的新手，我正在复制一个网站并将其存储在csv文件中，但我无法验证它是否存在于csv文件中。我想正确的做法应该是滚动这些行来检查标题是否已经存在。有人知道怎么解这个吗?请看下面的代码:

from pathlib import Path
import time
import csv
from selenium import webdriver
from bs4 import BeautifulSoup
import pandas as pd
DRIVER_PATH = str(Path('geckodriver').resolve())

def write_csv(ads):
filename = 'results.csv'
with open(filename, 'a+') as f:
fields = ['title', 'url']
writer = csv.DictWriter(f, fieldnames=fields)
existing_lines = csv.reader(f)
for ad in ads:
if ad['title'] not in existing_lines:
print(existing_lines)
writer.writerow(ad)

print('success')
else:
print('fail')

def get_html(url):
browser = webdriver.Firefox(executable_path=DRIVER_PATH)
browser.get(url)
return browser.page_source

def scrapde_data(card):
try:
h2 = card.h2
except:
title = ''
url = ''
else:
title = h2.text.strip()
try:
url = card.find('a').get('href')
except:
url = ''
data = {'title': title, 'url': url}
return data

def main():
while True:
url = '#'
html = get_html(url)
soup = BeautifulSoup(html, 'lxml')
cards = soup.find_all('div', {"class": "produto--comprar"})
ads_data = []
for card in cards:
data = scrapde_data(card)
ads_data.append(data)
write_csv(ads_data)
time.sleep(5)
if __name__ == '__main__':
main()

请帮帮我。(

Answer 1

尝试以下代码:-

def write_csv(ads):

filename = 'results.csv'
with open(filename, 'a+', newline='') as f:
fields = ['title', 'url']
writer = csv.DictWriter(f, fieldnames=fields)
#moving file pointer at the start of the file
f.seek(0)
existing_lines = csv.reader(f)

#finding no of lines in the file
count=0
for line in existing_lines:
count+=1
break
#if file is not empty
if count>0:
for ad in ads:
flag=0
#moving file pointer to the start of the file
f.seek(0)
#checking if ad['title'] is present in the first column of csv file
for line in existing_lines:
if ad['title'] in line[0]:
flag=1 
#if ad['title'] is not found                   
if flag==0:
writer.writerow(ad)

#if file is empty write the dictionary contents into the csv
else:
for ad in ads:
writer.writerow(ad)