无法有条件地删除某些csv文件

Question

我已经用python编写了一个脚本，以从网页中获取一些表格内容，并将其写入到csv文件中。 我现在想做的是，仅当该页面中有表格（可见为Top Mutual Fund Holders ）可用时，让我的脚本将内容写入csv文件中，否则它将删除已创建的csv文件。

该表在此网页上可用。

我要查找的表在此网页中不可用。

这是我的尝试：

import os
import csv
import requests
from bs4 import BeautifulSoup

url = "https://finance.yahoo.com/quote/UBER/holders?p=UBER"

def get_mutual_fund(soup):
    datalist = []
    for items in soup.select_one("h3:contains('Top Mutual Fund Holders')").find_next_sibling().select("table tr"):
        data = [item.text for item in items.select("th,td")]
        datalist.append(data)
    return datalist

def get_records(link):
    r = requests.get(link)
    soup_obj = BeautifulSoup(r.text,"lxml")
    try:
        item_one = get_mutual_fund(soup_obj)
    except AttributeError: 
        item_one = ""

    if item_one:
        writer.writerows(item_one)
    else:
        os.remove("mutual_fund.csv")
    return item_one

if __name__ == '__main__':
    with open("mutual_fund.csv","w",newline="") as f:
        writer = csv.writer(f)
        for elem in get_records(url):
            print(elem)

我尝试了没有该表的链接。 但是，它引发以下错误

while deleting the csv file:
Traceback (most recent call last):
  File "C:\Users\WCS\AppData\Local\Programs\Python\Python37-32\demo.py", line 33, in <module>
    for elem in get_records(url):
  File "C:\Users\WCS\AppData\Local\Programs\Python\Python37-32\demo.py", line 27, in get_records
    os.remove("mutual_fund.csv")
PermissionError: [WinError 32] The process cannot access the file because it is being used by another process: 'mutual_fund.csv'

当表格内容不存在时，如何删除csv文件？

Answer 1

当您打开文件时，实际上是在删除文件。

您应该相应地更改主要功能。

def get_records(link):
    r = requests.get(link)
    soup_obj = BeautifulSoup(r.text,"lxml")
    try:
        item_one = get_mutual_fund(soup_obj)
    except AttributeError: 
        item_one = None
    return item_one


if __name__ == '__main__':
    delete_file= False
    with open("mutual_fund.csv","w",newline="") as f:
        writer = csv.writer(f)
        try:
            for elem in get_records(url):
                print(elem)    
        except TypeError:
            delete_file=True
    if delete_file:
        os.remove("mutual_fund.csv")

Answer 2

如果您保持现有逻辑不变，并且在csv中的内容为空时删除文件，则应执行以下操作：

import os
import csv
import requests
from bs4 import BeautifulSoup

# url = "https://finance.yahoo.com/quote/fb/holders?p=FB"
url = "https://finance.yahoo.com/quote/UBER/holders?p=UBER"

def get_mutual_fund(soup):
    datalist = []
    for items in soup.select_one("h3:contains('Top Mutual Fund Holders')").find_next_sibling().select("table tr"):
        data = [item.text for item in items.select("th,td")]
        datalist.append(data)
    return datalist

def get_records(link):
    r = requests.get(link)
    soup_obj = BeautifulSoup(r.text,"lxml")
    try:
        item_one = get_mutual_fund(soup_obj)
    except AttributeError: 
        item_one = ""

    if item_one:
        writer.writerows(item_one)
    else:
        f.close()
        os.remove('mutual_fund.csv')

if __name__ == '__main__':
    with open("mutual_fund.csv","w",newline="") as f:
        writer = csv.writer(f)
        get_records(url)