之前就爬过拉勾网，但是遇到一些错误一直没有办法解决，果断放弃了，今天又重新试着写写看，对于一个菜鸟来说，真的都是处处是坑，写篇文章记录一些，供接下去学习参考。
首先就是打开拉勾网，在搜索栏中输入Python，打开F12，刷新：
在这个原始的请求的response中是没有我们要的数据的，一般这种情况下我就切换到XHR中取中取找：
URL:https://www.lagou.com/jobs/positionAjax.jsonneedAddtionalResult=false&isSchoolJob=0中可以找到我们想要的JSON数据。所以可以模拟浏览器对这个URL进行请求，再对返回的JSON数据进行解析就可以得到我们想要的结果。
所以在scrapy中的spider.py开始编写代码：
import scrapy
classLagouSpider(scrapy.Spider):
name='lagou'
def start_requests(self):
url='https://www.lagou.com/jobs/positionAjax.jsonneedAddtionalResul
t=false&isSchoolJob=0'
yield scrapy.FormRequest(url,formdata={'first':'true','pn':'1','kd':'python'},method='Post',meta={'pn':1},callback=self.parse)
def parse(self,response):
html=response.text
data=json.loads(html)
if data:
content=data.get('content')
positionResult=content.get('positionResult')
results=positionResult.get('result')
for result in results:
companyFullName=result.get('companyFullName')
print(companyFullName)
在settings.py下使用的是默认的DEFAULT_REQUEST_HEADERS，并在里面我添加了随机的User-Agent,然后我开始运行代码，结果出现报错：
File "E:\Python\pycharm\lagouposition\lagouposition\spiders\lagou.py", line 60, in parse
content=data['content']
KeyError: 'content'
明明代码看起来没有什么问题，为什么一直就是提示这个错误呢，着实让我很奔溃，后面在知乎上看到了有人回答说要把request headers全部加上（具体为什么回答的人也说还不知道），然后我就在settings.py设置如下：
DEFAULT_REQUEST_HEADERS = {
'Accept': 'application/json, text/javascript, */*; q=0.01',
'Accept-Encoding':'gzip, deflate, br',
'Accept-Language': 'zh-CN,zh;q=0.8',
'Connection':'keep-alive',
'Content-Type':'application/x-www-form-urlencoded; charset=UTF-8',
'Cookie':'LGUID=20170624104910-b3421612-5887-11e7-805a-525400f775ce; user_trace_token=20170624104912-161b9c7475a6448381c393fd68935f6b; index_location_city=%E5%85%A8%E5%9B%BD; JSESSIONID=ABAAABAAAFCAAEGF2DB2AA232B68C2B16743FE83939C1E9; _gat=1; PRE_UTM=; PRE_HOST=; PRE_SITE=; PRE_LAND=https%3A%2F%2Fwww.lagou.com%2F; TG-TRACK-CODE=index_search; _gid=GA1.2.705404459.1505118253; _ga=GA1.2.1378071003.1498273550; LGSID=20170911225046-98307e76-9700-11e7-8f76-525400f775ce; LGRID=20170911225056-9dbaf56b-9700-11e7-9168-5254005c3644; Hm_lvt_4233e74dff0ae5bd0a3d81c6ccf756e6=1504697344,1504751304,1504860546,1505142452; Hm_lpvt_4233e74dff0ae5bd0a3d81c6ccf756e6=1505142462; SEARCH_ID=1875185cf5904051845b74a20b82bebd',
'Host':'www.lagou.com',
'Origin':'https://www.lagou.com',
'Referer':'https://www.lagou.com/jobs/list_python?labelWords=&fromSearch=true&suginput=',
# 'User-Agent':'User-Agent:Mozilla/5.0 (Windows NT 6.1) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/58.0.3029.110 Safari/537.36',
'X-Anit-Forge-Code':'0',
'X-Anit-Forge-Token':'None',
'X-Requested-With':'XMLHttpRequest'}
然后运行，上面的报错是消失了，但是却出现了一个编码的报错（我使用的是window7系统）:
同样的在网上找了很多，试了一些方法还是没什么用，一直报这个错误，最后找到了一种解决方法，在spider.py中添加了如下代码：
import sys，io
sys.stdout=io.TextIOWrapper(sys.stdout.buffer,encoding='gbk')
解决了上面的编码问题。
然后继续编码，在items.py:
from scrapy importItem,Field
classLagoupositionItem(Item):
companyFullName=Field()
companyId=Field()
companyLabelList=Field()
companyLogo=Field()
companyShortName=Field()
companySize=Field()
createTime=Field()
deliver=Field()
district=Field()
education=Field()
explain=Field()
financeStage=Field()
firstType=Field()
formatCreateTime=Field()
gradeDescription=Field()
industryField=Field()
industryLables=Field()
isSchoolJob=Field()
jobNature=Field()
positionAdvantage=Field()
positionId=Field()
positionLables=Field()
positionName=Field()
salary=Field()
secondType=Field()
workYear=Field()
在spider.py
def parse(self,response):
html=response.text
data=json.loads(html)
ifdata:
content=data.get('content')
positionResult=content.get('positionResult')
totalCount=positionResult.get('totalCount')
pages=int(totalCount/15)
if pages>=30:
pages=30
else:
pages=pages
results=positionResult.get('result')
for result in results:
item=LagoupositionItem()
item['companyFullName']=result.get('companyFullName')
item['companyId']=result.get('companyId')
item['companyLabelList']=result.get('companyLabelList')
item['companyLogo']=result.get('companyLogo')
item['companyShortName']=result.get('companyShortName')
item['companySize']=result.get('companySize')
item['createTime']=result.get('createTime')
item['deliver']=result.get('deliver')
item['district']=result.get('district')
item['education']=result.get('education')
item['explain']=result.get('explain')
item['financeStage']=result.get('financeStage')
item['firstType']=result.get('firstType')
item['formatCreateTime']=result.get('formatCreateTime')
item['gradeDescription']=result.get('gradeDescription')
item['industryField']=result.get('industryField')
item['industryLables']=result.get('industryLables')
item['isSchoolJob']=result.get('isSchoolJob')
item['jobNature']=result.get('jobNature')
item['positionAdvantage']=result.get('positionAdvantage')
item['positionId']=result.get('positionId')
item['positionLables']=result.get('positionLables')
item['positionName']=result.get('positionName')
item['salary']=result.get('salary')
item['secondType']=result.get('secondType')
item['workYear']=result.get('workYear')
yield item
pn=int(response.meta.get('pn'))+1
if pn<=pages:
yield scrapy.FormRequest(response.url,formdata={'first':'False','pn':str(pn),'kd':'python'},method='Post',meta{'pn':pn},callback=self.parse)
原本以为能够把前面的30页都抓取下来，没想到只是抓取了一页的内容后，就可以报前面的错误：
File "E:\Python\pycharm\lagouposition\lagouposition\spiders\lagou.py", line 60, in parse
content=data['content']
KeyError: 'content'
考虑到前面一开始也报这个错误，我觉得是后面的：
yield scrapy.FormRequest(response.url,formdata{'first':'False','pn':str(pn),'kd':'python'},
method='Post',meta{'pn':pn},callback=self.parse)
没有headers的缘故。所以做了如下的调整，将settings.py中的DEFAULT_REQUEST_HEADERS注释掉然后在spider.py中添加如下：
headers={
'Accept': 'application/json, text/javascript, */*; q=0.01',
'Accept-Encoding':'gzip, deflate, br',
'Accept-Language': 'zh-CN,zh;q=0.8',
'Connection':'keep-alive',
'Content-Type':'application/x-www-form-urlencoded; charset=UTF-8',
'Cookie':'LGUID=20170624104910-b3421612-5887-11e7-805a-525400f775ce; user_trace_token=20170624104912-161b9c7475a6448381c393fd68935f6b; index_location_city=%E5%85%A8%E5%9B%BD; JSESSIONID=ABAAABAAAFCAAEGF2DB2AA232B68C2B16743FE83939C1E9; _gat=1; PRE_UTM=; PRE_HOST=; PRE_SITE=; PRE_LAND=https%3A%2F%2Fwww.lagou.com%2F; TG-TRACK-CODE=index_search; _gid=GA1.2.705404459.1505118253; _ga=GA1.2.1378071003.1498273550; LGSID=20170911225046-98307e76-9700-11e7-8f76-525400f775ce; LGRID=20170911225056-9dbaf56b-9700-11e7-9168-5254005c3644; Hm_lvt_4233e74dff0ae5bd0a3d81c6ccf756e6=1504697344,1504751304,1504860546,1505142452; Hm_lpvt_4233e74dff0ae5bd0a3d81c6ccf756e6=1505142462; SEARCH_ID=1875185cf5904051845b74a20b82bebd',
'Host':'www.lagou.com',
'Origin':'https://www.lagou.com',
'Referer':'https://www.lagou.com/jobs/list_python?labelWords=&fromSearch=true&suginput=',
# 'User-Agent':'User-Agent:Mozilla/5.0 (Windows NT 6.1) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/58.0.3029.110 Safari/537.36',
'X-Anit-Forge-Code':'0',
'X-Anit-Forge-Token':'None',
'X-Requested-With':'XMLHttpRequest'}
并修改：
yield scrapy.FormRequest(url,formdata{'first':'true','pn':'1','kd':'python'},method='Post',
meta{'pn':1},headers=self.headers,callback=self.parse)
同时修改：
yield scrapy.FormRequest(response.url,formdata={'first':'False','pn':str(pn),'kd':'python'},
method='Post',meta{'pn':pn},headers=self.headers,callback=self.parse)
然后运行，终于可以跑起来了抓了30页的内容。这个过程中oooO ↘┏━┓ ↙ Oooo
( 踩)→┃你┃ ←(死 )\ ( →┃√┃ ← ) /\_)↗┗━┛ ↖(_/的坑比较多。
