edustack_addition.py

#views.py
from opaque_keys.edx.locations import SlashSeparatedCourseKey
from courseware.courses import get_course_by_id
from .models import Addition
from rest_framework.response import Response
from rest_framework.decorators import api_view,permission_classes,authentication_classes
from rest_framework.authentication import SessionAuthentication,OAuth2Authentication
from django.core.exceptions import ObjectDoesNotExist
from django.conf import settings
from student.models import CourseEnrollment
from opaque_keys.edx.locations import SlashSeparatedCourseKey

@api_view(['POST'])
@authentication_classes((SessionAuthentication,OAuth2Authentication))
def add_enrollment_number(request):
    #return {"info":"hello"}
    course_id = request.DATA["course_id"]
    enrollment_number = int(request.DATA["add_field"])
    try:
        obj = Addition.objects.get(course_id=course_id)
        obj.enrollment_number= enrollment_number
        obj.save()
    except ObjectDoesNotExist:
        Addition.objects.create(course_id=course_id,enrollment_number=enrollment_number)
    return Response({"info":"ok"})

@api_view(['POST'])
@authentication_classes((SessionAuthentication,OAuth2Authentication))
def get_enrollment_number(request):
    #return {"info":"ok"}
    course_id = request.DATA["course_id"]
    if settings.FEATURES.get('DISPLAY_ANALYTICS_ENROLLMENTS'):
       course_key = SlashSeparatedCourseKey.from_deprecated_string(course_id)
       enrollment_number = CourseEnrollment.num_enrolled_in(course_key)
       return Response({"enrollment_number":enrollment_number})
    try:
        obj = Addition.objects.get(course_id=course_id)
        enrollment_number = obj.enrollment_number
    except ObjectDoesNotExist:
         obj = Addition.objects.create(course_id=course_id,enrollment_number=0)
         enrollment_number = obj.enrollment_number
    return Response({"enrollment_number":enrollment_number})

#urls.py    
#add by wwj
urlpatterns += (
    url(r'^additions/add_enrollment_number$', "additions.views.add_enrollment_number"),
    url(r'^additions/get_enrollment_number$', "additions.views.get_enrollment_number"),
)

#js
  $.post("/additions/get_enrollment_number",{"course_id":"edX/DemoX/Demo_Course"},function(result){
    console.log(result);
  });