Python3，Beautifulsoup4標籤混亂

Question

我試圖得到一些數據來自Amazon我的代碼是：

import requests, bs4 

source_code = requests.get("https://www.amazon.com/s/ref=sr_nr_p_n_feature_keywords_0?fst=as%3Aoff&rh=n%3A2335752011%2Cn%3A%212335753011%2Cn%3A7072561011%2Cn%3A2407749011%2Cp_89%3AHuawei%2Cp_n_feature_keywords_four_browse-bin%3A6787346011&bbn=2407749011&ie=UTF8&qid=1473923594&rnid=6787345011", 
    headers={ 
    "User-Agent": "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_11_4) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/49.0.2623.110 Safari/537.36" 
}) 
source_code.raise_for_status() 

soup = bs4.BeautifulSoup(source_code.text, 'lxml') 
mobile_div = soup.find_all("div", class_="a-row a-spacing-small") 
for mobile_name in mobile_div: 
    print(mobile_name.a.find_next("h2").string) 

它輸出不錯，但不是當我使用

print(mobile_name.a.h2.string) 

它顯示了以下錯誤：

print(mobile_name.a.h2.string) 
AttributeError: 'NoneType' object has no attribute 'string' 

我的標記是：

任何人都可以解釋爲什麼我得到這個錯誤？

Answer 1

因爲第一錨返回是：

<a class="a-button-text" href="/gp/help/contact-us/general-questions.html/ref=sr_hms_cs/155-8370713-5732665?browse_node_id=468556&amp;ie=UTF8&amp;qid=1473939395" role="button">contact us</a> 

它沒有H2子/後代，稱find_next看起來錨的H2後無所不在，所以，即使它沒有一個孩子會找到下一個。 a.h2查找錨的子/後代，以便返回None的第一個錨。

find_all_next() and find_next()

這些方法使用.next_elements遍歷任何標籤和它之後來到文檔的字符串。該find_all_next（）方法返回的所有比賽，並find_next（）只返回的第一個匹配：

這個簡單的例子應該

In [34]: html = """<div> 
      <a class="a-button-text" href="/fof.com">foobar</a> 
      <h2 class="sibling"> blah</h2> 
      <div ><h2 class="nexted"> blah</h2></div> 
      </div>""" 

In [34]: soup = bs4.BeautifulSoup(html, 'lxml') 

In [35]: a = soup.div.a 
In [36]: print(a.h2) # a has no direct descendants so we get None 
None 
In [37]: a.find_next("h2") # finds the next h2 anywhere after the anchor 
Out[37]: <h2 class="sibling"> blah</h2> 


In [38]: a.find_next_siblings("h2") # finds any h2's in the tree that are siblings 
Out[38]: [<h2 class="sibling"> blah</h2>] 

In [39]: a.find_all_next("h2") # finds all h2s anywhere after 
Out[39]: [<h2 class="sibling"> blah</h2>, <h2 class="nexted"> blah</h2>]