refactor to use get_xform_users_with_perms which uses a less expensiv…

…e query

onadata/apps/main/views.py

@@ -18,7 +18,7 @@
 from django.utils.translation import ugettext as _
 from django.views.decorators.http import (require_GET, require_http_methods,
                                           require_POST)
-from guardian.shortcuts import assign_perm, get_users_with_perms, remove_perm
+from guardian.shortcuts import assign_perm, remove_perm
 from rest_framework.authtoken.models import Token
 
 from onadata.apps.logger.models import Instance, XForm
@@ -51,7 +51,9 @@
 from onadata.libs.utils.user_auth import (add_cors_headers, check_and_set_user,
                                           check_and_set_user_and_form,
                                           get_user_default_project,
-                                          get_xform_and_perms, has_permission,
+                                          get_xform_and_perms,
+                                          get_xform_users_with_perms,
+                                          has_permission,
                                           helper_auth_helper, set_profile_data)
 from onadata.libs.utils.viewer_tools import (EnketoError, enketo_url,
                                              get_enketo_preview_url, get_form)
@@ -356,7 +358,7 @@ def set_xform_owner_data(data, xform, request, username, id_string):
     data['external_export_form'] = ExternalExportForm()
     users_with_perms = []
 
-    for perm in get_users_with_perms(xform, attach_perms=True).items():
+    for perm in get_xform_users_with_perms(xform).items():
         has_perm = []
         if 'change_xform' in perm[1]:
             has_perm.append(_(u"Can Edit"))

onadata/libs/utils/user_auth.py

@@ -121,6 +121,23 @@ def get_xform_and_perms(username, id_string, request):
     return [xform, is_owner, can_edit, can_view]
 
 
+def get_xform_users_with_perms(xform):
+    """Similar to django-guadian's get_users_with_perms here the query makes
+    use of the xformuserobjectpermission_set to return a dictionary of users
+    with a list of permissions to the XForm object. The query in use is not as
+    expensive as the one in use with get_users_with_perms
+    """
+    user_perms = {}
+    for p in xform.xformuserobjectpermission_set.all().select_related(
+        'user', 'permission').only(
+            'user', 'permission__codename', 'content_object_id'):
+        if p.user.username not in user_perms:
+            user_perms[p.user] = []
+        user_perms[p.user].append(p.permission.codename)
+
+    return user_perms
+
+
 def helper_auth_helper(request):
     if request.user and request.user.is_authenticated():
         return None