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From：https://www.jb51.net/article/146769.htm

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使用 requests 發(fā)送 post 請求

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先來看看使用requests來發(fā)送post請求是多少好用，發(fā)送請求
Requests 簡便的 API 意味著所有 HTTP 請求類型都是顯而易見的。
例如，你可以這樣發(fā)送一個 HTTP POST 請求：

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

使用data可以傳遞字典作為參數(shù)，同時也可以傳遞元祖

>>>payload = (('key1', 'value1'), ('key1', 'value2')) >>>r = requests.post('http://httpbin.org/post', data=payload) >>>print(r.text) {..."form": {"key1": ["value1","value2"]},... }

傳遞 json 是這樣

>>>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)

也就是說，你不需要對參數(shù)做什么變化，只需要關(guān)注使用data=還是json=，其余的requests都已經(jīng)幫你做好了。

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使用scrapy發(fā)送post請求

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通過源碼可知scrapy默認發(fā)送的get請求，當我們需要發(fā)送攜帶參數(shù)的請求或登錄時，是需要post、請求的，以下面為例

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',#這里不能給bool類型的True，requests模塊中可以'pn': '1',#這里不能給int類型的1，requests模塊中可以'kd': 'python'}, # 這里的formdata相當于requ模塊中的data，key和value只能是鍵值對形式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']))

官方推薦的 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)]

這里使用的是FormRequest，并使用formdata傳遞參數(shù)，看到這里也是一個字典。

但是，超級坑的一點來了，今天折騰了一下午，使用這種方法發(fā)送請求，怎么發(fā)都會出問題，返回的數(shù)據(jù)一直都不是我想要的

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

在網(wǎng)上找了很久，最終找到一種方法，使用scrapy.Request發(fā)送請求，就可以正常的獲取數(shù)據(jù)。

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

參考：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'} )

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FormRequest 與 Request 區(qū)別

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在文檔中，幾乎看不到差別，

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.

說FormRequest新增加了一個參數(shù)formdata，接受包含表單數(shù)據(jù)的字典或者可迭代的元組，并將其轉(zhuǎn)化為請求的body。并且FormRequest是繼承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 formdataquerystr = _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 seqfor v in (vs if is_listlike(vs) else [vs])]return urlencode(values, doseq=1)

最終我們傳遞的{‘key': ‘value', ‘k': ‘v'}會被轉(zhuǎn)化為'key=value&k=v' 并且默認的method是POST，再來看看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 firstself.method = str(method).upper()

默認的方法是GET，其實并不影響。仍然可以發(fā)送post請求。這讓我想起來requests中的request用法，這是定義請求的基礎(chǔ)方法。

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 stringdefining the content type of the given file and ``custom_headers`` a dict-like object containing additional headersto 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 databefore giving up, as a float, or a :ref:`(connect timeout, readtimeout) <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 verifythe server's TLS certificate, or a string, in which case it must be a pathto 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.ResponseUsage::>>> 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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