Below POST Method is not working in scrapy - python-2.7

Question

I have tried with headers, cookies, Formdata and body too, but i got 401 and 500 status code. In this site First Page is in GET method & gives HTML response and further pages are in POST method & gives JSON response. But these status codes arrives for unauthorisation but i have searched and i couldn't find any CSRF token or auth token in web page headers.
import scrapy
from SouthShore.items import Product
from scrapy.http import Request, FormRequest
class OjcommerceDSpider(scrapy.Spider):
handle_httpstatus_list = [401,500]
name = "ojcommerce_d"
allowed_domains = ["ojcommerce.com"]
#start_urls = ['http://www.ojcommerce.com/search?k=south%20shore%20furniture']
def start_requests(self):
return [FormRequest('http://www.ojcommerce.com/ajax/search.aspx/FetchDataforPaging',
method ="POST",
body = '''{"searchTitle" : "south shore furniture","pageIndex" : '2',"sortBy":"1"}''',
headers={'Content-Type': 'application/json; charset=UTF-8', 'Accept' : 'application/json, text/javascript, */*; q=0.01',
'Cookie' :'''vid=eAZZP6XwbmybjpTWQCLS+g==;
_ga=GA1.2.1154881264.1480509732;
ASP.NET_SessionId=rkklowbpaxzpp50btpira1yp'''},callback=self.parse)]
def parse(self,response):
with open("ojcommerce.json","wb") as f:
f.write(response.body)

Answer 1

I got it working with the following code:
import json
from scrapy import Request, Spider
class OjcommerceDSpider(Spider):
name = "ojcommerce"
allowed_domains = ["ojcommerce.com"]
custom_settings = {
'LOG_LEVEL': 'DEBUG',
'COOKIES_DEBUG': True,
'DEFAULT_REQUEST_HEADERS': {
'User-Agent': 'Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/52.0.2743.82 Safari/537.36',
},
}
def start_requests(self):
yield Request(
url='http://www.ojcommerce.com/search?k=furniture',
callback=self.parse_search_page,
)
def parse_search_page(self, response):
yield Request(
url='http://www.ojcommerce.com/ajax/search.aspx/FetchDataforPaging',
method='POST',
body=json.dumps({'searchTitle': 'furniture', 'pageIndex': '2', 'sortBy': '1'}),
callback=self.parse_json_page,
headers={
'Content-Type': 'application/json; charset=UTF-8',
'Accept': 'application/json, text/javascript, */*; q=0.01',
'X-Requested-With': 'XMLHttpRequest',
},
)
def parse_json_page(self,response):
data = json.loads(response.body)
with open('ojcommerce.json', 'wb') as f:
json.dump(data, f, indent=4)
Two observations:
a previous request to another site page is needed to get a "fresh" ASP.NET_SessionId cookie
I couldn't make it work using FormRequest, use Request instead.