I am trying to crawl the latest reviews from google play store and to get that I need to make a post request.

With the Postman, it works and I get desired response.

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but a post request in terminal gives me a server error

For ex: this page https://play.google.com/store/apps/details?id=com.supercell.boombeach

curl -H "Content-Type: application/json" -X POST -d '{"id": "com.supercell.boombeach", "reviewType": '0', "reviewSortOrder": '0', "pageNum":'0'}' https://play.google.com/store/getreviews

gives a server error and

Scrapy just ignores this line:

frmdata = {"id": "com.supercell.boombeach", "reviewType": 0, "reviewSortOrder": 0, "pageNum":0}
        url = "https://play.google.com/store/getreviews"
        yield Request(url, callback=self.parse, method="POST", body=urllib.urlencode(frmdata))

The answer above do not really solved the problem. They are sending the data as paramters instead of JSON data as the body of the request.

From http://bajiecc.cc/questions/1135255/scrapy-formrequest-sending-json:

my_data = {'field1': 'value1', 'field2': 'value2'}
request = scrapy.Request( url, method='POST', 
                          body=json.dumps(my_data), 
                          headers={'Content-Type':'application/json'} )

Make sure that each element in your formdata is of type string/unicode

frmdata = {"id": "com.supercell.boombeach", "reviewType": '0', "reviewSortOrder": '0', "pageNum":'0'}
url = "https://play.google.com/store/getreviews"
yield FormRequest(url, callback=self.parse, formdata=frmdata)

I think this will do

In [1]: from scrapy.http import FormRequest

In [2]: frmdata = {"id": "com.supercell.boombeach", "reviewType": '0', "reviewSortOrder": '0', "pageNum":'0'}

In [3]: url = "https://play.google.com/store/getreviews"

In [4]: r = FormRequest(url, formdata=frmdata)

In [5]: fetch(r)
 2015-05-20 14:40:09+0530 [default] DEBUG: Crawled (200) <POST      https://play.google.com/store/getreviews> (referer: None)
[s] Available Scrapy objects:
[s]   crawler    <scrapy.crawler.Crawler object at 0x7f3ea4258890>
[s]   item       {}
[s]   r          <POST https://play.google.com/store/getreviews>
[s]   request    <POST https://play.google.com/store/getreviews>
[s]   response   <200 https://play.google.com/store/getreviews>
[s]   settings   <scrapy.settings.Settings object at 0x7f3eaa205450>
[s]   spider     <Spider 'default' at 0x7f3ea3449cd0>
[s] Useful shortcuts:
[s]   shelp()           Shell help (print this help)
[s]   fetch(req_or_url) Fetch request (or URL) and update local objects
[s]   view(response)    View response in a browser

Sample Page Traversing using Post in Scrapy:

def directory_page(self,response):
    if response:
        profiles = response.xpath("//div[@class="heading-h"]/h3/a/@href").extract()
        for profile in profiles:
            yield Request(urljoin(response.url,profile),callback=self.profile_collector)

        page = response.meta['page'] + 1
        if page :
            yield FormRequest('https://rotmanconnect.com/AlumniDirectory/getmorerecentjoineduser',
                                        formdata={'isSortByName':'false','pageNumber':str(page)},
                                        callback= self.directory_page,
                                        meta={'page':page})
    else:
         print "No more page available"