manifold/manifoldproxy.py

   1 import json
   2 # this is for django objects only
   3 #from django.core import serializers
   4 from django.http import HttpResponse, HttpResponseForbidden
   5
   6 from manifold.manifoldquery import ManifoldQuery
   7 from manifold.manifoldapi import ManifoldAPI
   8
   9 debug=False
  10 debug=True
  11
  12 # add artificial delay in s
  13 debug_spin=0
  14 #debug_spin=1
  15
  16 # turn this on if you want the fastest possible (locally cached) feedback
  17 # beware that this is very rough though...
  18 work_offline=False
  19 #work_offline=True
  20
  21 # this view is what the javascript talks to when it sends a query
  22 # see also
  23 # myslice/urls.py
  24 # as well as
  25 # static/js/manifold.js
  26 def proxy (request,format):
  27     """the view associated with /manifold/proxy/
  28 with the query passed using POST"""
  29
  30     # expecting a POST
  31     if request.method != 'POST':
  32         print "manifoldproxy.api: unexpected method %s -- exiting"%request.method
  33         return
  34     # we only support json for now
  35     # if needed in the future we should probably cater for
  36     # format_in : how is the query encoded in POST
  37     # format_out: how to serve the results
  38     if format != 'json':
  39         print "manifoldproxy.api: unexpected format %s -- exiting"%format
  40         return
  41     try:
  42         # translate incoming POST request into a query object
  43         if debug: print 'manifoldproxy.proxy: request.POST',request.POST
  44         manifold_query = ManifoldQuery()
  45         manifold_query.fill_from_POST(request.POST)
  46         offline_filename="offline-%s-%s.json"%(manifold_query.action,manifold_query.subject)
  47         # retrieve session for request
  48         manifold_api_session_auth = request.session['manifold']['auth']
  49         ### patch : return the latest one..
  50         if work_offline:
  51             # if that won't work then we'll try to update anyways
  52             try:
  53                 with (file(offline_filename,"r")) as f:
  54                     json_answer=f.read()
  55                 print "By-passing : using contents from %s"%offline_filename
  56                 return HttpResponse (json_answer, mimetype="application/json")
  57             except:
  58                 import traceback
  59                 traceback.print_exc()
  60                 print "PROCEEDING"
  61                 pass
  62
  63         # actually forward
  64         manifold_api= ManifoldAPI(auth=manifold_api_session_auth)
  65         if debug: print 'manifoldproxy.proxy: sending to backend', manifold_query
  66         answer=manifold_api.send_manifold_query (manifold_query)
  67         if debug:
  68             try:        print "received answer from backend with %d rows"%len(answer)
  69             except:     print "received answer from backend - can't say len"
  70         json_answer=json.dumps(answer)
  71         if (debug):
  72             with (file(offline_filename,"w")) as f:
  73                 f.write(json_answer)
  74         if debug_spin:
  75             import time
  76             time.sleep(debug_spin)
  77         # return json-encoded answer
  78         return HttpResponse (json_answer, mimetype="application/json")
  79     except:
  80         import traceback
  81         traceback.print_exc()
  82
  83 ####################
  84 # see CSRF_FAILURE_VIEW in settings.py
  85 # the purpose of redefining this was to display the failure reason somehow
  86 # this however turns out disappointing/not very informative
  87 failure_answer=[ "csrf_failure" ]
  88 def csrf_failure(request, reason=""):
  89     print "CSRF failure with reason '%s'"%reason
  90     return HttpResponseForbidden (json.dumps (failure_answer), mimetype="application/json")