send user_logged_in signal from my_user_info

A user's last logged in value previously wasn't updated when the user
logs in through the oauth2 flow from the ios mobile app. Here we must
send the user_logged_in signal manually. It's implemented in the
my_user_info mobile rest api endpoint because adding it to where the
oauth2 flow happens is to complex, and the mobile app hits this endpoint
after a successful login anyway.

lms/djangoapps/mobile_api/users/tests.py

@@ -77,6 +77,21 @@ class TestUserInfoApi(MobileAPITestCase, MobileAuthTestMixin):
         response = self.api_response(expected_response_code=302, api_version=api_version)
         self.assertIn(self.username, response['location'])
 
+    @ddt.data(API_V05, API_V1)
+    def test_last_loggedin_updated(self, api_version):
+        """Verify that a user's last logged in value updates after hitting the my_user_info endpoint"""
+        self.login()
+
+        self.user.refresh_from_db()
+        last_login_before = self.user.last_login
+
+        # just hit the api endpoint; we don't care about the response here (tested previously)
+        self.api_response(expected_response_code=302, api_version=api_version)
+
+        self.user.refresh_from_db()
+        last_login_after = self.user.last_login
+        assert last_login_after > last_login_before
+
 
 @ddt.ddt
 @override_settings(MKTG_URLS={'ROOT': 'dummy-root'})

lms/djangoapps/mobile_api/users/views.py

@@ -5,6 +5,7 @@ Views for user API
 from __future__ import absolute_import
 
 import six
+from django.contrib.auth.signals import user_logged_in
 from django.shortcuts import redirect
 from django.utils import dateparse
 from opaque_keys import InvalidKeyError
@@ -14,6 +15,7 @@ from rest_framework.decorators import api_view
 from rest_framework.response import Response
 from xblock.fields import Scope
 from xblock.runtime import KeyValueStore
+from django.contrib.auth.models import User
 
 from lms.djangoapps.courseware.access import is_mobile_available_for_user
 from lms.djangoapps.courseware.courses import get_current_child
@@ -336,4 +338,7 @@ def my_user_info(request, api_version):
     """
     Redirect to the currently-logged-in user's info page
     """
+    # update user's last logged in from here because
+    # updating it from the oauth2 related code is too complex
+    user_logged_in.send(sender=User, user=request.user, request=request)
     return redirect("user-detail", api_version=api_version, username=request.user.username)