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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：

>>>r = requests.post('http://httpbin.org/post', data = {'key':'value'})

使用data可以传递字典作为参数，同时也可以传递元祖

>>>payload = (('key1', 'value1'), ('key1', 'value2'))

>>>r = requests.post('http://httpbin.org/post', data=payload)

>>>print(r.text)

{

...

"form": {

"key1": [

"value1",

"value2"

]

},

...

}

传递 json 是这样

>>>import json

>>>url = 'https://api.github.com/some/endpoint'

>>>payload = {'some': 'data'}

>>>r = requests.post(url, data=json.dumps(payload))

2.4.2 版的新加功能：

>>>url = 'https://api.github.com/some/endpoint'

>>>payload = {'some': 'data'}

>>>r = requests.post(url, json=payload)

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

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

'kd': 'python'

}, # 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']))

官方推荐的 Using FormRequest to send data via HTTP POST

return [FormRequest(url="http://www.example.com/post/action",

formdata={'name': 'John Doe', 'age': '27'},

callback=self.after_post)]

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

return scrapy.FormRequest(url, formdata=(payload))

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。

return scrapy.Request(url, body=json.dumps(payload), method='POST', headers={'Content-Type': 'application/json'},)

参考：Send Post Request in Scrapy

my_data = {'field1': 'value1', 'field2': 'value2'}

request = scrapy.Request( url, method='POST',

body=json.dumps(my_data),

headers={'Content-Type':'application/json'} )

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

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)

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

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()

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。

def request(method, url, **kwargs):

"""Constructs and sends a :class:`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) ` 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 ` object

:rtype: requests.Response

Usage::

>>> import requests

>>> req = requests.request('GET', 'http://httpbin.org/get')

"""

# 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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来源： https://blog.csdn.net/freeking101/article/details/82908342