Update api_views.py In your API while creting user group field is not working i.e user not mapped with the group.

So we added above API for the same.

mayan/apps/user_management/api_views.py

@@ -1,9 +1,11 @@
 from __future__ import unicode_literals
 
 from django.contrib.auth import get_user_model
-from django.contrib.auth.models import Group
+from django.contrib.auth.models import Group, User
 
 from rest_framework import generics
+from rest_framework.response import Response
+from rest_framework.views import APIView
 
 from rest_api.filters import MayanObjectPermissionsFilter
 from rest_api.permissions import MayanPermission
@@ -14,6 +16,7 @@ from .permissions import (
     permission_user_edit, permission_user_view
 )
 from .serializers import GroupSerializer, UserSerializer
+from rest_framework import authentication, permissions
 
 
 class APIGroupListView(generics.ListCreateAPIView):
@@ -174,3 +177,41 @@ class APICurrentUserView(generics.RetrieveUpdateDestroyAPIView):
         """
 
         return super(APICurrentUserView, self).put(*args, **kwargs)
+    
+class APIUserGroupMap(APIView):
+    """
+    View to map user with groups
+    
+    
+    **Arguments:**
+        - request: Http request object.
+        - pk:primary key of User
+
+    **Returns:** User Details
+
+    **Raises:** Nothing.
+
+    This methods handles http POST request.
+
+    This method map users with group.
+    
+
+    * Requires token authentication.\n
+    * Only admin users are able to access this view.
+    """
+    authentication_classes = (authentication.TokenAuthentication,)
+    permission_classes = (permissions.IsAdminUser,)
+    
+    def post(self, request,pk,format=None):
+        """
+        Maps user with groups
+        """
+        groups = request.POST['group_ids'].split(',')
+        userObj = User.objects.get(pk=pk)
+        for group in groups:
+            groupObj = Group.objects.get(pk=group)
+            groupObj.user_set.add(userObj)
+        mapped_group_ids = userObj.groups.all().values_list('id', flat=True)
+        result = { "id":userObj.id,"groups":mapped_group_ids,"username":userObj.username,
+              "fname":userObj.first_name,"lname":userObj.last_name }
+        return Response({ 'data':result })