Python：“如果 i.find('a')['id'] 不是 None：

Question

我正在尝试做的事情：我正在尝试编写一个脚本来抓取网站以获取产品信息。目前，该程序使用 for 循环来获取产品价格和唯一 ID。for 循环包含两个 if 语句以阻止它抓取 NoneType。import requestsfrom bs4 import BeautifulSoupdef average(price_list):    return sum(price_list) / len(price_list)# Requests search data from Websitepage_link = 'URL'page_response = requests.get(page_link, timeout=5)  # gets the webpage (search) from Websitepage_content = BeautifulSoup(page_response.content, 'html.parser')  # turns the webpage it just retrieved into a BeautifulSoup-object# Selects the product listings from page content so we can work with theseproduct_listings = page_content.find_all("div", {"class": "unit flex align-items-stretch result-item"})prices = []  # Creates a list to add the prices touids = [] # Creates a list to store the unique idsfor product in product_listings:## UIDS     if product.find('a')['id'] is not None:        uid = product.find('a')['id']        uids.append(uid)# PRICES    if product.find('p', class_ = 'result-price man milk word-break') is not None:# assures that the loop only finds the prices        price = int(product.p.text[:-2].replace(u'\xa0', ''))  # makes a temporary variable where the last two chars of the string (,-) and whitespace are removed, turns into int        prices.append(price)  # adds the price to the list问题：上if product.find('a')['id'] is not None:，我得到一个Exception has occurred: TypeError'NoneType' object is not subscriptable.不管是谁，如果我跑了print(product.find('a')['id'])，我就会得到我正在寻找的价值，这让我很困惑。这不意味着错误不是 NoneType 吗？此外，if product.find('p', class_ = 'result-price man milk word-break') is not None:工作完美无缺。我试过的：我试过分配if product.find('p', class_ = 'result-price man milk word-break')给一个变量，然后在 for 循环中运行它，但这不起作用。我也做了我应得的谷歌搜索，但没有占上风。问题可能是我对编程比较陌生，不知道要搜索什么，但我仍然找到了很多似乎与相关问题有关的答案，但这在我的工作中不起作用代码。任何帮助将不胜感激！

Answer 1

只需做一个中间步骤：

res = product.find('a')

if res is not None and res['id'] is not None:

    uids.append(res['id'])

这样，如果 findNone由于未找到该项目而返回，则您最终不会尝试下标 NoneType。