Scrapy FormRequest redirect not wanted link - scrapy

Question

I followed the basic Scrapy Login. It always works, but in this case, I had some problems. The FormRequest.from_response didn't request the https://www.crowdfunder.com/user/validateLogin, instead it always sent payload to https://www.crowdfunder.com/user/signup. I tried directly request the validateLogin with payload, but it responded with 404 Error. Any idea to help me solve this problem? Thanks in advance!!!
class CrowdfunderSpider(InitSpider):
name = "crowdfunder"
allowed_domains = ["crowdfunder.com"]
start_urls = [
'http://www.crowdfunder.com/',
]
login_page = 'https://www.crowdfunder.com/user/login/'
payload = {}
def init_request(self):
"""This function is called before crawling starts."""
return scrapy.Request(url=self.login_page, callback=self.login)
def login(self, response):
"""Generate a login request."""
self.payload = {'email': 'my_email',
'password': 'my_password'}
# scrapy login
return scrapy.FormRequest.from_response(response, formdata=self.payload, callback=self.check_login_response)
def check_login_response(self, response):
"""Check the response returned by a login request to see if we are
successfully logged in.
"""
if 'https://www.crowdfunder.com/user/settings' == response.url:
self.log("Successfully logged in. :) :) :)")
# start the crawling
return self.initialized()
else:
# login fail
self.log("login failed :( :( :(")
Here is the payload and request link sent by clicking login in browser:
payload and request url sent by clicking login button
Here is the log info:
2016-10-21 21:56:21 [scrapy] INFO: Scrapy 1.1.0 started (bot: crowdfunder_crawl)
2016-10-21 21:56:21 [scrapy] INFO: Overridden settings: {'AJAXCRAWL_ENABLED': True, 'NEWSPIDER_MODULE': 'crowdfunder_crawl.spiders', 'SPIDER_MODULES': ['crowdfunder_crawl.spiders'], 'ROBOTSTXT_OBEY': True, 'BOT_NAME': 'crowdfunder_crawl'}
2016-10-21 21:56:21 [scrapy] INFO: Enabled extensions:
['scrapy.extensions.logstats.LogStats',
'scrapy.extensions.telnet.TelnetConsole',
'scrapy.extensions.corestats.CoreStats']
2016-10-21 21:56:21 [scrapy] INFO: Enabled downloader middlewares:
['scrapy.downloadermiddlewares.robotstxt.RobotsTxtMiddleware',
'scrapy.downloadermiddlewares.httpauth.HttpAuthMiddleware',
'scrapy.downloadermiddlewares.downloadtimeout.DownloadTimeoutMiddleware',
'scrapy.downloadermiddlewares.useragent.UserAgentMiddleware',
'scrapy.downloadermiddlewares.retry.RetryMiddleware',
'scrapy.downloadermiddlewares.defaultheaders.DefaultHeadersMiddleware',
'scrapy.downloadermiddlewares.ajaxcrawl.AjaxCrawlMiddleware',
'scrapy.downloadermiddlewares.redirect.MetaRefreshMiddleware',
'scrapy.downloadermiddlewares.httpcompression.HttpCompressionMiddleware',
'scrapy.downloadermiddlewares.redirect.RedirectMiddleware',
'scrapy.downloadermiddlewares.cookies.CookiesMiddleware',
'scrapy.downloadermiddlewares.chunked.ChunkedTransferMiddleware',
'scrapy.downloadermiddlewares.stats.DownloaderStats']
2016-10-21 21:56:21 [scrapy] INFO: Enabled spider middlewares:
['scrapy.spidermiddlewares.httperror.HttpErrorMiddleware',
'scrapy.spidermiddlewares.offsite.OffsiteMiddleware',
'scrapy.spidermiddlewares.referer.RefererMiddleware',
'scrapy.spidermiddlewares.urllength.UrlLengthMiddleware',
'scrapy.spidermiddlewares.depth.DepthMiddleware']
2016-10-21 21:56:21 [scrapy] INFO: Enabled item pipelines:
[]
2016-10-21 21:56:21 [scrapy] INFO: Spider opened
2016-10-21 21:56:21 [scrapy] INFO: Crawled 0 pages (at 0 pages/min), scraped 0 items (at 0 items/min)
2016-10-21 21:56:21 [scrapy] DEBUG: Telnet console listening on 127.0.0.1:6024
2016-10-21 21:56:21 [scrapy] DEBUG: Crawled (200) <GET https://www.crowdfunder.com/robots.txt> (referer: None)
2016-10-21 21:56:21 [scrapy] DEBUG: Redirecting (301) to <GET http://www.crowdfunder.com/user/login> from <GET https://www.crowdfunder.com/user/login/>
2016-10-21 21:56:22 [scrapy] DEBUG: Redirecting (301) to <GET https://www.crowdfunder.com/user/login> from <GET http://www.crowdfunder.com/user/login>
2016-10-21 21:56:22 [scrapy] DEBUG: Crawled (200) <GET https://www.crowdfunder.com/user/login> (referer: None)
2016-10-21 21:56:23 [scrapy] DEBUG: Crawled (200) <POST https://www.crowdfunder.com/user/signup> (referer: https://www.crowdfunder.com/user/login)
2016-10-21 21:56:23 [crowdfunder] DEBUG: login failed :( :( :(
2016-10-21 21:56:23 [scrapy] INFO: Closing spider (finished)
2016-10-21 21:56:23 [scrapy] INFO: Dumping Scrapy stats:
{'downloader/request_bytes': 1569,
'downloader/request_count': 5,
'downloader/request_method_count/GET': 4,
'downloader/request_method_count/POST': 1,
'downloader/response_bytes': 16313,
'downloader/response_count': 5,
'downloader/response_status_count/200': 3,
'downloader/response_status_count/301': 2,
'finish_reason': 'finished',
'finish_time': datetime.datetime(2016, 10, 22, 4, 56, 23, 232493),
'log_count/DEBUG': 7,
'log_count/INFO': 7,
'request_depth_max': 1,
'response_received_count': 3,
'scheduler/dequeued': 4,
'scheduler/dequeued/memory': 4,
'scheduler/enqueued': 4,
'scheduler/enqueued/memory': 4,
'start_time': datetime.datetime(2016, 10, 22, 4, 56, 21, 180030)}
2016-10-21 21:56:23 [scrapy] INFO: Spider closed (finished)

Answer 1

FormRequest.from_response(response) by default uses the first form it finds. If you check what forms the page has you'd see:
In : response.xpath("//form")
Out:
[<Selector xpath='//form' data='<form action="/user/signup" method="post'>,
<Selector xpath='//form' data='<form action="/user/login" method="POST"'>,
<Selector xpath='//form' data='<form action="/user/login" method="post"'>]
So the form you are looking for is not 1st one. The way to fix it is to use one of many from_response method parameters to specify which form to use.
Using formxpath is the most flexible and my personal favorite:
In : FormRequest.from_response(response, formxpath='//*[contains(#action,"login")]')
Out: <POST https://www.crowdfunder.com/user/login>