使用 bs4 时出现问题：'NoneType' 对象不可订阅

Question

我正在尝试抓取 Goodreads 页面以获取一本书的所有版本，但是当我运行代码时出现此错误：

Traceback (most recent call last):
  File "C:/xxx/PycharmProjects/wikipedia_pageview/isbn.py", line 141, in <module>
    ed_details = get_editions_details(isbn) 
  File "C:/xxx/PycharmProjects/wikipedia_pageview/isbn.py", line 79, in get_editions_details
    if ed_link := f"https://www.goodreads.com{ed_item['href']}":...
TypeError: 'NoneType' object is not subscriptable

出于这个原因，我尝试在所选区域设置条件，但它们不起作用。代码：

def get_editions_details(isbn):
# Create the search URL with the ISBN of the book
data = {'q': isbn}
book_url = get_page("https://www.goodreads.com/search", data)
#print(book_url)
# Parse the markup with Beautiful Soup
soup = bs(book_url.text, 'lxml')
# Retrieve from the book's page the link for other editions
# and the total number of editions
if ed_item := soup.find("div", class_="otherEditionsLink"):
    if ed_item := ed_item.find("a"):
        print(ed_item)
    else:
        pass

if ed_item:
    ed_num = ed_item.text.strip().split(' ')[-1].strip('()')

if ed_link := f"https://www.goodreads.com{ed_item['href']}":#capire...
    print(ed_link)
else:
    pass
return((ed_link, int(ed_num), isbn))  



if __name__ == "__main__":
        try:
            os.mkdir('./urls_files')
        except Exception:
            pass


    isbns = get_isbn()

    for isbn in isbns:
            ed_details = get_editions_details(isbn) 
            get_editions_urls(ed_details)

Answer 1

会发生什么？

您的示例中的缩进似乎不正确，不会处理错误或丢失的 isbn 或版本链接。

如何修复？

在确定 ed_item 中存在 href 的那一刻将值分配给 ed_link 和 ed_num，否则将它们设置为 None或 0 或以其他方式处理这些问题：

def get_editions_details(isbn):

    data = {'q': isbn}
    book_url = requests.get("https://www.goodreads.com/search", data)
    soup = bs(book_url.text, 'lxml')

    ed_link = None
    ed_num = 0

    if ed_item := soup.find("div", class_="otherEditionsLink"):
        if ed_item := ed_item.find("a"):
            ed_link = f"https://www.goodreads.com{ed_item['href']}"
            ed_num = ed_item.text.strip().split(' ')[-1].strip('()')
        else:
            pass

    return((ed_link, int(ed_num), isbn))


if __name__ == "__main__":
    #just as example to simulate an error
    ed_details = get_editions_details(1)
    if ed_details[0]:
        get_editions_urls(ed_details)
    else:
        print(f'no editionlinks for isbn:{ed_details[2]}')

使用 bs4 时出现问题：'NoneType' 对象不可订阅

Problem while using bs4: 'NoneType' object is not subscriptable

python

beautifulsoup

request

web-scraping

python-3.x

会发生什么？

如何修复？