python使用scrapy傳送post請求的坑
使用 requests 傳送 post 請求
先來看看使用requests來發送post請求是多少好用,傳送請求 Requests 簡便的 API 意味著所有 HTTP 請求型別都是顯而易見的。 例如,你可以這樣傳送一個 HTTP POST 請求:
>>>r = requests.post('http://httpbin.org/post', data = {'key':'value'})
使用data可以傳遞字典作為引數,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,你不需要對引數做什麼變化,只需要關注使用data=還是json=,其餘的requests都已經幫你做好了。
使用scrapy傳送post請求
通過原始碼可知scrapy預設傳送的get請求,當我們需要傳送攜帶引數的請求或登入時,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',#這裡不能給bool型別的True,requests模組中可以 'pn': '1',#這裡不能給int型別的1,requests模組中可以 'kd': 'python' }, # 這裡的formdata相當於requ模組中的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)]
這裡使用的是FormRequest,並使用formdata傳遞引數,看到這裡也是一個字典。
但是,超級坑的一點來了,今天折騰了一下午,使用這種方法傳送請求,怎麼發都會出問題,返回的資料一直都不是我想要的
return scrapy.FormRequest(url, formdata=(payload))
在網上找了很久,最終找到一種方法,使用scrapy.Request傳送請求,就可以正常的獲取資料。
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'} )
FormRequest 與 Request 區別
在文件中,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新增加了一個引數formdata,接受包含表單資料的字典或者可迭代的元組,並將其轉化為請求的body。並且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 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)
最終我們傳遞的{‘key': ‘value', ‘k': ‘v'}會被轉化為'key=value&k=v' 並且預設的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 first
self.method = str(method).upper()
預設的方法是GET,其實並不影響。仍然可以傳送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 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)