XPath的使用[爬取知乎发现]文件存储[txt，json，csv，mongodb]

使用XPath

 1 import requests
 2 import json
 3 from lxml import etree
 4 from urllib import parse
 5 
 6 url = 'https://www.zhihu.com/explore'
 7 headers = {
 8     'User-Agent': 'Mozilla/5.0 (Macintosh; Intel Mac OS X 10_12_3) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/58.0.3029.110 Safari/537.36'
 9 }
10 html = requests.get(url, headers=headers).text
11 # 响应返回的是字符串，解析为HTML DOM模式 text = etree.HTML(html)
12 text = etree.HTML(html)
13 # 返回所有内容的结点位置
14 node_list = text.xpath('//div[@class="explore-feed feed-item"]')
15 items ={}
16 for node in node_list:
17     # xpath返回的列表，这个列表就这一个参数，用索引方式取出来
18     #问题
19     question = node.xpath('.//h2/a')[0].text.replace("
","")
20     # 作者
21     author = node.xpath('.//*[@class="author-link-line"]/*')[0].text
22     #author = "".join(node.xpath('.//*[@class="author-link-line"]//text()')).replace("
","")
23     # 回答
24     answer = node.xpath('.//*[@class="content"]')[0].text
25     #answer = "".join(node.xpath('.//*[@class="content"]/text()')).strip()
26     #answer = str(node.xpath('.//*[@class="content"]/text()'))[1:-1]
27 
28     items = {
29         "question" : question,
30         "author" : author,
31         "answer" : answer,
32     } 
33 
34     with open("explore.json", "a") as f:
35         #f.write(json.dumps(items, ensure_ascii = False).encode("utf-8") + "
")
36         f.write(json.dumps(items, ensure_ascii = False) + "
")

保存为TXT  

 1 import requests
 2  3 from lxml import etree
 4 from urllib import parse
 5 
 6 url = 'https://www.zhihu.com/explore'
 7 headers = {
 8     'User-Agent': 'Mozilla/5.0 (Macintosh; Intel Mac OS X 10_12_3) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/58.0.3029.110 Safari/537.36'
 9 }
10 html = requests.get(url, headers=headers).text
11 # 响应返回的是字符串，解析为HTML DOM模式 text = etree.HTML(html)
12 text = etree.HTML(html)
13 # 返回所有内容的结点位置
14 node_list = text.xpath('//div[@class="explore-feed feed-item"]')
15 
16 for node in node_list:
17     # xpath返回的列表，这个列表就这一个参数，用索引方式取出来
18     #问题
19     question = node.xpath('.//h2/a')[0].text.replace("
","")
20     # 作者
21     author = node.xpath('.//*[@class="author-link-line"]/*')[0].text
22     #author = "".join(node.xpath('.//*[@class="author-link-line"]//text()')).replace("
","")
23     # 回答
24     answer = node.xpath('.//*[@class="content"]')[0].text
25     #answer = "".join(node.xpath('.//*[@class="content"]/text()')).strip()
26     #answer = str(node.xpath('.//*[@class="content"]/text()'))[1:-1]
27 
28     with open('explore.txt', 'a', encoding='utf-8') as file:
29         file.write('
'.join([question, author, answer]))
30         file.write('
' + '=' * 50 + '
')

 保存为csv

 1 import requests
 2 from lxml import etree
 3 from urllib import parse
 4 import csv
 5 
 6 url = 'https://www.zhihu.com/explore'
 7 headers = {
 8     'User-Agent': 'Mozilla/5.0 (Macintosh; Intel Mac OS X 10_12_3) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/58.0.3029.110 Safari/537.36'
 9 }
10 html = requests.get(url, headers=headers).text
11 # 响应返回的是字符串，解析为HTML DOM模式 text = etree.HTML(html)
12 text = etree.HTML(html)
13 # 返回所有内容的结点位置
14 node_list = text.xpath('//div[@class="explore-feed feed-item"]')
15 
16 for node in node_list:
17     # xpath返回的列表，这个列表就这一个参数，用索引方式取出来
18     #问题
19     question = node.xpath('.//h2/a')[0].text.replace("
","")
20     # 作者
21     author = node.xpath('.//*[@class="author-link-line"]/*')[0].text
22     #author = "".join(node.xpath('.//*[@class="author-link-line"]//text()')).replace("
","")
23     # 回答,为方便展示，只取部分内容,text[ :10]
24     answer = node.xpath('.//*[@class="content"]')[0].text[ :10]
25 
26     #answer = node.xpath('.//*[@class="content"]')[0].text
27     #answer = "".join(node.xpath('.//*[@class="content"]/text()')).strip()
28     #answer = str(node.xpath('.//*[@class="content"]/text()'))[1:-1]
29 
30 
31     with open('explore.csv', 'a', encoding='utf-8') as csvfile:
32         fieldnames = ['question', 'author', 'answer']
33         writer = csv.DictWriter(csvfile, fieldnames=fieldnames)
34         writer.writeheader()
35         writer.writerow({'question': question, 'author': author, 'answer': answer})

读取csv

1 import csv
2 
3 with open('explore.csv', 'r', encoding='utf-8') as csvfile:
4     reader = csv.reader(csvfile)
5     for row in reader:
6         print(row)

Excel打开乱码参考：excel打开csv文件显示乱码的处理方法_百度经验

保存到MongoDB

 1 import requests
 2 from lxml import etree
 3 from urllib import parse
 4 from pymongo import MongoClient
 5 
 6 client = MongoClient()
 7 db = client['explore']
 8 collection = db['explore']
 9 
10 url = 'https://www.zhihu.com/explore'
11 headers = {
12     'User-Agent': 'Mozilla/5.0 (Macintosh; Intel Mac OS X 10_12_3) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/58.0.3029.110 Safari/537.36'
13 }
14 html = requests.get(url, headers=headers).text
15 # 响应返回的是字符串，解析为HTML DOM模式 text = etree.HTML(html)
16 text = etree.HTML(html)
17 # 返回所有内容的结点位置
18 node_list = text.xpath('//div[@class="explore-feed feed-item"]')
19 
20 for node in node_list:
21     # xpath返回的列表，这个列表就这一个参数，用索引方式取出来
22     #问题
23     question = node.xpath('.//h2/a')[0].text.replace("
","")
24     # 作者
25     author = node.xpath('.//*[@class="author-link-line"]/*')[0].text
26     #author = "".join(node.xpath('.//*[@class="author-link-line"]//text()')).replace("
","")
27     # 回答
28     answer = node.xpath('.//*[@class="content"]')[0].text
29     #answer = "".join(node.xpath('.//*[@class="content"]/text()')).strip()
30     #answer = str(node.xpath('.//*[@class="content"]/text()'))[1:-1]
31 
32     items = {
33         "question" : question,
34         "author" : author,
35         "answer" : answer,
36     } 
37 
38     if collection.insert(items):
39         print('Saved to Mongo')

稍微改动

 1 import requests
 2 from lxml import etree
 3 from urllib import parse
 4 from pymongo import MongoClient
 5 
 6 client = MongoClient()
 7 db = client['explore']
 8 collection = db['explore']
 9 
10 url = 'https://www.zhihu.com/explore'
11 headers = {
12     'User-Agent': 'Mozilla/5.0 (Macintosh; Intel Mac OS X 10_12_3) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/58.0.3029.110 Safari/537.36'
13 }
14 html = requests.get(url, headers=headers).text
15 # 响应返回的是字符串，解析为HTML DOM模式 text = etree.HTML(html)
16 text = etree.HTML(html)
17 # 返回所有内容的结点位置
18 node_list = text.xpath('//div[@class="explore-feed feed-item"]')
19 explore ={}
20 for node in node_list:
21     # xpath返回的列表，这个列表就这一个参数，用索引方式取出来
22     #问题
23     explore['question'] = node.xpath('.//h2/a')[0].text.replace("
","")
24     # 作者
25     explore['author'] = node.xpath('.//*[@class="author-link-line"]/*')[0].text
26     #author = "".join(node.xpath('.//*[@class="author-link-line"]//text()')).replace("
","")
27     # 回答
28     explore['answer'] = node.xpath('.//*[@class="content"]')[0].text
29     #answer = "".join(node.xpath('.//*[@class="content"]/text()')).strip()
30     #answer = str(node.xpath('.//*[@class="content"]/text()'))[1:-1]
31 
32     if collection.insert(explore):
33         print('Saved to Mongo')

抛出异常

    raise DuplicateKeyError(error.get("errmsg"), 11000, error)

pymongo.errors.DuplicateKeyError: E11000 duplicate key error collection: explore.explore index: _id_ dup key: { : ObjectId('5b3792ae393e0d0c38123bbc') }

id用于记录唯一的一条Schema，Schema本身就有标识唯一性的属性，它就是：ObjectId主键，一种特殊而且非常重要的类型，每个Schema都会默认配置这个属性，属性名为_id
MongoDB 默认会创建一个索引_id

 1 import requests
 2 from lxml import etree
 3 from urllib import parse
 4 from pymongo import MongoClient
 5 import pymongo.errors
 6 
 7 client = MongoClient()
 8 db = client['explore']
 9 collection = db['explore']
10 
11 url = 'https://www.zhihu.com/explore'
12 headers = {
13     'User-Agent': 'Mozilla/5.0 (Macintosh; Intel Mac OS X 10_12_3) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/58.0.3029.110 Safari/537.36'
14 }
15 html = requests.get(url, headers=headers).text
16 # 响应返回的是字符串，解析为HTML DOM模式 text = etree.HTML(html)
17 text = etree.HTML(html)
18 # 返回所有内容的结点位置
19 node_list = text.xpath('//div[@class="explore-feed feed-item"]')
20 explore ={}
21 for node in node_list:
22     # xpath返回的列表，这个列表就这一个参数，用索引方式取出来
23     #问题
24     explore['question'] = node.xpath('.//h2/a')[0].text.replace("
","")
25     # 作者
26     explore['author'] = node.xpath('.//*[@class="author-link-line"]/*')[0].text
27     #author = "".join(node.xpath('.//*[@class="author-link-line"]//text()')).replace("
","")
28     # 回答
29     explore['answer'] = node.xpath('.//*[@class="content"]')[0].text
30     #answer = "".join(node.xpath('.//*[@class="content"]/text()')).strip()
31     #answer = str(node.xpath('.//*[@class="content"]/text()'))[1:-1]
32     try:
33         if collection.insert(explore):
34             print('Saved to Mongo')
35     except pymongo.errors.DuplicateKeyError:
36         # 对唯一字段进行重复插入，pymongo则会抛出这个错误，并且插入失败
37         print("重复插入")
38         pass

还是不能插入数据。

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原文地址：https://www.cnblogs.com/wanglinjie/p/9248573.html