python - 使用 BeautifulSoup 抓取时如何处理某些页面中缺失的元素
问题描述
我需要从一系列产品页面中抓取下面的代码,然后将其拆分以分别显示作者和插图画家。
问题是:
某些页面同时具有<li>
作者和<li>
插图画家,如第 1 页
某些页面只有<li>
for author,如 page2
某些页面既没有作者也没有插图画家,所以根本没有<ul>
,如第 3页
<li>
知道 是否适用于插画家的唯一方法是,是否<li>
包含文本“(Illustreerder)”。
当作者和插图画家为空时,如何为它们分配默认值?
<ul class="product-brands">
<li class="brand-item">
<a href="https://lapa.co.za/Skrywer/zinelda-mcdonald-illustreerder.html" title="Zinelda McDonald (Illustreerder)">Zinelda McDonald (Illustreerder)</a>
</li>
<li class="brand-item">
<a href="https://lapa.co.za/Skrywer/jose-reinette-palmer.html" title="Jose Palmer & Reinette Lombard">Jose Palmer & Reinette Lombard</a>
</li>
</ul>
from bs4 import BeautifulSoup
import requests
headers = {
'User-Agent': 'Mozilla/5.0 (iPad; CPU OS 12_2 like Mac OS X) AppleWebKit/605.1.15 (KHTML, like Gecko) Mobile/15E148'
}
# AUTHOR & ILLUSTRATOR
page1 = 'https://lapa.co.za/kinder-en-tienerboeke/leer-my-lees-vlak-r-grootboek-10-tippie-help-vir-frikkie'
# AUTHOR ONLY
page2 = 'https://lapa.co.za/catalog/product/view/id/1649/s/hoendervleis-grillerige-stories-en-rympies/category/84/'
# NO AUTHOR and NO ILLUSTRATOR
page3 = 'https://lapa.co.za/catalog/product/view/id/1633/s/sanri-steyn-7-vampiere-van-vlermuishoogte/category/84/'
# PAGE WITH NO STOCK
page4 = 'https://lapa.co.za/kinder-en-tienerboeke/my-groot-lofkleuterbybel-2-oudiomusiek'
illustrator = '(Illustreerder)'
productlist = []
r = requests.get(page2, headers=headers)
soup = BeautifulSoup(r.content, 'lxml')
isbn = soup.find('div', class_='value', itemprop='sku').text.replace(" ", "")
stocks = soup.find('div', class_='stock available')
if stocks is not None:
stock = stocks.text.strip()
if stocks is None:
stock = 'n/a'
for ultag in soup.find_all('ul', {'class': 'product-brands'}):
for litag in ultag.find_all('li'):
author = litag.text.strip() or 'None'
if illustrator not in author:
author = author
for ultag in soup.find_all('ul', {'class': 'product-brands'}):
for litag in ultag.find_all('li'):
author = litag.text.strip()
if illustrator in author:
illustrator = author
bookdata = [isbn, stock, author, illustrator]
print(bookdata)
预期输出:
r = requests.get(page1, headers=headers)
['9781776356515', 'In voorraad', 'Jose Palmer & Reinette Lombard', 'Zinelda McDonald']
预期输出:
r = requests.get(page2, headers=headers)
['9780799383874', 'In voorraad', 'Jaco Jacobs', 'None']
预期输出:
r = requests.get(page3, headers=headers)
['9780799383690', 'In voorraad', 'None', 'None']
解决方案
你可以这样做。
首先选择
<ul>
您需要使用的find()
ul = soup.find('ul', class_='product-brands')
现在检查是否
<ul>
存在。如果True
那么您至少有一个作者或插画家或两者兼而有之。如果
True
,则获取元素<li>
内标签的字符串<ul>
并返回列表。您可以使用.stripped_strings
来获取标签内所有字符串的列表。如果
False
简单地返回None
。if ul: return list(ul.stripped_strings) return None
根据返回的列表中的项目数量,我认为很容易弄清楚您在问题中提到的内容是什么:
<li>
知道 是否适用于插画家的唯一方法是,是否<li>
包含文本“(Illustreerder)”。
这是给出作者和 Illustrator 列表的代码(如果它们中的任何一个存在) else None
。
import requests
from bs4 import BeautifulSoup
# AUTHOR & ILLUSTRATOR
page1 = 'https://lapa.co.za/kinder-en-tienerboeke/leer-my-lees-vlak-r-grootboek-10-tippie-help-vir-frikkie'
# AUTHOR ONLY
page2 = 'https://lapa.co.za/catalog/product/view/id/1649/s/hoendervleis-grillerige-stories-en-rympies/category/84/'
# NO AUTHOR and NO ILLUSTRATOR
page3 = 'https://lapa.co.za/catalog/product/view/id/1633/s/sanri-steyn-7-vampiere-van-vlermuishoogte/category/84/'
# PAGE WITH NO STOCK
page4 = 'https://lapa.co.za/kinder-en-tienerboeke/my-groot-lofkleuterbybel-2-oudiomusiek'
def test(url):
headers = {
'User-Agent': 'Mozilla/5.0 (iPad; CPU OS 12_2 like Mac OS X) AppleWebKit/605.1.15 (KHTML, like Gecko) Mobile/15E148'
}
r = requests.get(url, headers=headers)
soup = BeautifulSoup(r.text, 'lxml')
ul = soup.find('ul', class_='product-brands')
# Setting Default values for author and illustrator
author, illustrator = None, None
# Return a list only if ul is not None
if ul:
details = list(ul.stripped_strings)
# Assigning the names to "author" and "illustrator"
for name in details:
if name.endswith('(Illustreerder)'):
illustrator = name
else:
author = name
return (author, illustrator)
# Iterate over the pages and call the test() function to get author and illustrator names
for page in [page1, page2, page3, page4]:
author, illustrator = test(page)
print(f'Authors: {author}\nIllustrators: {illustrator}\n')
现在,您已经将名称分开author
并illustrator
存储在每个页面的不同变量中。
Authors: Jose Palmer & Reinette Lombard
Illustrators: Zinelda McDonald (Illustreerder)
Authors: Jaco Jacobs
Illustrators: None
Authors: None
Illustrators: None
Authors: Jan de Wet
Illustrators: None
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