title: Sending an ASP.net POST with Python's Requests
body: <p>I'm scraping an old ASP.net website using Python's requests module.</p>
  
  <p>I've spent 5+ hours trying to figure out how to simulate this POST request to no avail. Doing it the way I do it below, I essentially get a message saying "No item matches this item reference."</p>
  
  <p>Any help would be deeply appreciated – here's the request and my code, a few things are modified out of respect to brevity and/or privacy:</p>
  
  <p><strong>My own code:</strong></p>
  
  <pre><code>import requests
  
  # Scraping the item number from the website, I have confirmed this is working.
  
  #Then use the newly acquired item number to request the data.
  item_url = http://www.example.com/EN/items/Pages/yourrates.aspx?vr= + item_number[0]
  viewstate = r'/wEPD...' # Truncated for brevity.
  
  # Create the appropriate request and payload.
  payload = {"vr": int(item_number[0])}
  
  item_request_body = {
          "__SPSCEditMenu": "true",
          "MSOWebPartPage_PostbackSource": "",
          "MSOTlPn_SelectedWpId": "",
          "MSOTlPn_View": 0,
          "MSOTlPn_ShowSettings": "False",
          "MSOGallery_SelectedLibrary": "",
          "MSOGallery_FilterString": "",
          "MSOTlPn_Button": "none",
          "__EVENTTARGET": "",
          "__EVENTARGUMENT": "",
          "MSOAuthoringConsole_FormContext": "",
          "MSOAC_EditDuringWorkflow": "",
          "MSOSPWebPartManager_DisplayModeName": "Browse",
          "MSOWebPartPage_Shared": "",
          "MSOLayout_LayoutChanges": "",
          "MSOLayout_InDesignMode": "",
          "MSOSPWebPartManager_OldDisplayModeName": "Browse",
          "MSOSPWebPartManager_StartWebPartEditingName": "false",
          "__VIEWSTATE": viewstate,
          "keywords": "Search our site",
          "__CALLBACKID": "ctl00$SPWebPartManager1$g_dbb9e9c7_fe1d_46df_8789_99a6c9db4b22",
          "__CALLBACKPARAM": "startvr"
      }
  
  # Write the appropriate headers for the property information.
  item_request_headers = {
      "Host": home_site,
      "Connection": "keep-alive",
      "Content-Length": len(encoded_valuation_request),
      "Cache-Control": "max-age=0",
      "Origin": home_site,
      "User-Agent": "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_9_4) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/36.0.1985.125 Safari/537.36",
      "Content-Type": "application/x-www-form-urlencoded; charset=UTF-8",
      "Cookie": "__utma=48409910.1174413745.1405662151.1406402487.1406407024.17; __utmb=48409910.7.10.1406407024; __utmc=48409910; __utmz=48409910.1406178827.13.3.utmcsr=ratesandvallandingpage|utmccn=landingpages|utmcmd=button",
      "Accept": "*/*",
      "Referer": valuation_url,
      "Accept-Encoding": "gzip,deflate,sdch",
      "Accept-Language": "en-US,en;q=0.8"
  }
  
      response = requests.post(url=item_url, params=payload, data=item_request_body, headers=item_request_headers)
      print response.text
  </code></pre>
  
  <p><strong>What Chrome is telling me the request looks like:</strong></p>
  
  <pre><code>Remote Address:202.55.96.131:80
  Request URL:http://www.example.com/EN/items/Pages/yourrates.aspx?vr=123456789
  Request Method:POST
  Status Code:200 OK
  
  Request Headers
  Accept:*/*
  Accept-Encoding:gzip,deflate,sdch
  Accept-Language:en-US,en;q=0.8
  Cache-Control:max-age=0
  Connection:keep-alive
  Content-Length:21501
  Content-Type:application/x-www-form-urlencoded; charset=UTF-8
  Cookie:__utma=48409910.1174413745.1405662151.1406402487.1406407024.17; __utmb=48409910.7.10.1406407024; __utmc=48409910; __utmz=48409910.1406178827.13.3.utmcsr=ratesandvallandingpage|utmccn=landingpages|utmcmd=button
  Host:www.site.com
  Origin:www.site.com
  Referer:http://www.example.com/EN/items/Pages/yourrates.aspx?vr=123456789
  User-Agent:Mozilla/5.0 (Macintosh; Intel Mac OS X 10_9_4) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/36.0.1985.125 Safari/537.36
  
  Query String Parameters
  vr:123456789
  
  Form Data
  __SPSCEditMenu:true
  MSOWebPartPage_PostbackSource:
  MSOTlPn_SelectedWpId:
  MSOTlPn_View:0
  MSOTlPn_ShowSettings:False
  MSOGallery_SelectedLibrary:
  MSOGallery_FilterString:
  MSOTlPn_Button:none
  __EVENTTARGET:
  __EVENTARGUMENT:
  MSOAuthoringConsole_FormContext:
  MSOAC_EditDuringWorkflow:
  MSOSPWebPartManager_DisplayModeName:Browse
  MSOWebPartPage_Shared:
  MSOLayout_LayoutChanges:
  MSOLayout_InDesignMode:
  MSOSPWebPartManager_OldDisplayModeName:Browse
  MSOSPWebPartManager_StartWebPartEditingName:false
  __VIEWSTATE:/wEPD...(Omitted for length)
  keywords:Search our site
  __CALLBACKID:ctl00$SPWebPartManager1$g_dbb9e9c7_fe1d_46df_8789_99a6c9db4b22
  __CALLBACKPARAM:startvr
  </code></pre>