使用requests发送post请求
先来看看使用requests来发送post请求是多少好用,发送请求
Requests 简便的 API 意味着所有 HTTP 请求类型都是显而易见的。例如,你可以这样发送一个 HTTP POST 请求:
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>>>r = requests.post( 'http://httpbin.org/post' , data = { 'key' : 'value' })
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使用data可以传递字典作为参数,同时也可以传递元祖
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>>>payload = (( 'key1' , 'value1' ), ( 'key1' , 'value2' ))
>>>r = requests.post( 'http://httpbin.org/post' , data = payload)
>>> print (r.text)
{
...
"form" : {
"key1" : [
"value1" ,
"value2"
]
},
...
}
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传递json是这样
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>>> import json
>>>url = 'https://api.github.com/some/endpoint'
>>>payload = { 'some' : 'data' }
>>>r = requests.post(url, data = json.dumps(payload))
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2.4.2 版的新加功能:
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>>>url = 'https://api.github.com/some/endpoint'
>>>payload = { 'some' : 'data' }
>>>r = requests.post(url, json = payload)
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也就是说,你不需要对参数做什么变化,只需要关注使用data=还是json=,其余的requests都已经帮你做好了。
使用scrapy发送post请求
通过源码可知scrapy默认发送的get请求,当我们需要发送携带参数的请求或登录时,是需要post、请求的,以下面为例
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from scrapy.spider import CrawlSpider
from scrapy.selector import Selector
import scrapy
import json
class LaGou(CrawlSpider):
name = 'myspider'
def start_requests( self ):
yield scrapy.FormRequest(
url = 'https://www.******.com/jobs/positionAjax.json?city=%E5%B9%BF%E5%B7%9E&needAddtionalResult=false' ,
formdata = {
'first' : 'true' , #这里不能给bool类型的True,requests模块中可以
'pn' : '1' , #这里不能给int类型的1,requests模块中可以
},这里的formdata相当于requ模块中的data,key和value只能是键值对形式
callback = self .parse
)
def parse( self , response):
datas = json.loads(response.body.decode())[ 'content' ][ 'positionResult' ][ 'result' ]
for data in datas:
print (data[ 'companyFullName' ] + str (data[ 'positionId' ]))
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官方推荐的 Using FormRequest to send data via HTTP POST
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return [FormRequest(url = "http://www.example.com/post/action" ,
formdata = { 'name' : 'John Doe' , 'age' : '27' },
callback = self .after_post)]
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这里使用的是FormRequest,并使用formdata传递参数,看到这里也是一个字典。
但是,超级坑的一点来了,今天折腾了一下午,使用这种方法发送请求,怎么发都会出问题,返回的数据一直都不是我想要的
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return scrapy.FormRequest(url, formdata = (payload))
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在网上找了很久,最终找到一种方法,使用scrapy.Request发送请求,就可以正常的获取数据。
参考:Send Post Request in Scrapy
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my_data = { 'field1' : 'value1' , 'field2' : 'value2' }
request = scrapy.Request( url, method = 'POST' ,
body = json.dumps(my_data),
headers = { 'Content-Type' : 'application/json' } )
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FormRequest 与 Request 区别
在文档中,几乎看不到差别,
The FormRequest class adds a new argument to the constructor. The remaining arguments are the same as for the Request class and are not documented here.
Parameters: formdata (dict or iterable of tuples) – is a dictionary (or iterable of (key, value) tuples) containing HTML Form data which will be url-encoded and assigned to the body of the request.
说FormRequest新增加了一个参数formdata,接受包含表单数据的字典或者可迭代的元组,并将其转化为请求的body。并且FormRequest是继承Request的
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class FormRequest(Request):
def __init__( self , * args, * * kwargs):
formdata = kwargs.pop( 'formdata' , None )
if formdata and kwargs.get( 'method' ) is None :
kwargs[ 'method' ] = 'POST'
super (FormRequest, self ).__init__( * args, * * kwargs)
if formdata:
items = formdata.items() if isinstance (formdata, dict ) else formdata
querystr = _urlencode(items, self .encoding)
if self .method = = 'POST' :
self .headers.setdefault(b 'Content-Type' , b 'application/x-www-form-urlencoded' )
self ._set_body(querystr)
else :
self ._set_url( self .url + ( '&' if '?' in self .url else '?' ) + querystr)
###
def _urlencode(seq, enc):
values = [(to_bytes(k, enc), to_bytes(v, enc))
for k, vs in seq
for v in (vs if is_listlike(vs) else [vs])]
return urlencode(values, doseq = 1 )
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最终我们传递的{‘key': ‘value', ‘k': ‘v'}会被转化为'key=value&k=v' 并且默认的method是POST,再来看看Request
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class Request(object_ref):
def __init__( self , url, callback = None , method = 'GET' , headers = None , body = None ,
cookies = None , meta = None , encoding = 'utf-8' , priority = 0 ,
dont_filter = False , errback = None , flags = None ):
self ._encoding = encoding # this one has to be set first
self .method = str (method).upper()
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默认的方法是GET,其实并不影响。仍然可以发送post请求。这让我想起来requests中的request用法,这是定义请求的基础方法。
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def request(method, url, * * kwargs):
"""Constructs and sends a :class:`Request <Request>`.
:param method: method for the new :class:`Request` object.
:param url: URL for the new :class:`Request` object.
:param params: (optional) Dictionary or bytes to be sent in the query string for the :class:`Request`.
:param data: (optional) Dictionary or list of tuples ``[(key, value)]`` (will be form-encoded), bytes, or file-like object to send in the body of the :class:`Request`.
:param json: (optional) json data to send in the body of the :class:`Request`.
:param headers: (optional) Dictionary of HTTP Headers to send with the :class:`Request`.
:param cookies: (optional) Dict or CookieJar object to send with the :class:`Request`.
:param files: (optional) Dictionary of ``'name': file-like-objects`` (or ``{'name': file-tuple}``) for multipart encoding upload.
``file-tuple`` can be a 2-tuple ``('filename', fileobj)``, 3-tuple ``('filename', fileobj, 'content_type')``
or a 4-tuple ``('filename', fileobj, 'content_type', custom_headers)``, where ``'content-type'`` is a string
defining the content type of the given file and ``custom_headers`` a dict-like object containing additional headers
to add for the file.
:param auth: (optional) Auth tuple to enable Basic/Digest/Custom HTTP Auth.
:param timeout: (optional) How many seconds to wait for the server to send data
before giving up, as a float, or a :ref:`(connect timeout, read
timeout) <timeouts>` tuple.
:type timeout: float or tuple
:param allow_redirects: (optional) Boolean. Enable/disable GET/OPTIONS/POST/PUT/PATCH/DELETE/HEAD redirection. Defaults to ``True``.
:type allow_redirects: bool
:param proxies: (optional) Dictionary mapping protocol to the URL of the proxy.
:param verify: (optional) Either a boolean, in which case it controls whether we verify
the server's TLS certificate, or a string, in which case it must be a path
to a CA bundle to use. Defaults to ``True``.
:param stream: (optional) if ``False``, the response content will be immediately downloaded.
:param cert: (optional) if String, path to ssl client cert file (.pem). If Tuple, ('cert', 'key') pair.
:return: :class:`Response <Response>` object
:rtype: requests.Response
Usage::
>>> import requests
>>> req = requests.request('GET', 'http://httpbin.org/get')
<Response [200]>
"""
# By using the 'with' statement we are sure the session is closed, thus we
# avoid leaving sockets open which can trigger a ResourceWarning in some
# cases, and look like a memory leak in others.
with sessions.Session() as session:
return session.request(method = method, url = url, * * kwargs)
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以上就是本文的全部内容,希望对大家的学习有所帮助,也希望大家多多支持服务器之家。
原文链接:https://zhangslob.github.io/2018/08/24/使用scrapy发送post请求的坑/