Merge pull request #10 from Harvard-University-iCommons/feature/fix_for_test_student

Modify logic for picking a default username value when lis_person_source...

django_auth_lti/backends.py

@@ -15,6 +15,7 @@ oauth_creds = settings.LTI_OAUTH_CREDENTIALS
 
 
 class LTIAuthBackend(ModelBackend):
+
     """
     By default, the ``authenticate`` method creates ``User`` objects for
     usernames that don't already exist in the database.  Subclasses can disable
@@ -24,6 +25,8 @@ class LTIAuthBackend(ModelBackend):
 
     # Create a User object if not already in the database?
     create_unknown_user = True
+    # Username prefix for users without an sis source id
+    unknown_user_prefix = "cuid:"
 
     def authenticate(self, request):
 
@@ -80,16 +83,14 @@ class LTIAuthBackend(ModelBackend):
 
         user = None
 
-        if request.POST.get('lis_person_sourcedid'):
-            username = self.clean_username(request.POST.get('lis_person_sourcedid'))
-        elif request.POST.get('custom_canvas_user_login_id'):
-            username = self.clean_username(request.POST.get('custom_canvas_user_login_id'))
-        else:
-            username = self.clean_username(request.POST.get('user_id'))
+        # Retrieve username from LTI parameter or default to an overridable function return value
+        username = tool_provider.lis_person_sourcedid or self.get_default_username(
+            tool_provider, prefix=self.unknown_user_prefix)
+        username = self.clean_username(username)  # Clean it
 
-        email = request.POST.get('lis_person_contact_email_primary')
-        first_name = request.POST.get('lis_person_name_given')
-        last_name = request.POST.get('lis_person_name_family')
+        email = tool_provider.lis_person_contact_email_primary
+        first_name = tool_provider.lis_person_name_given
+        last_name = tool_provider.lis_person_name_family
 
         logger.info("We have a valid username: %s" % username)
 
@@ -109,7 +110,8 @@ class LTIAuthBackend(ModelBackend):
                 logger.debug('authenticate found an existing user for %s' % username)
 
         else:
-            logger.debug('automatic new user creation is turned OFF! just try to find and existing record')
+            logger.debug(
+                'automatic new user creation is turned OFF! just try to find and existing record')
             try:
                 user = UserModel.objects.get_by_natural_key(username)
             except UserModel.DoesNotExist:
@@ -131,3 +133,12 @@ class LTIAuthBackend(ModelBackend):
 
     def clean_username(self, username):
         return username
+
+    def get_default_username(self, tool_provider, prefix=''):
+        """
+        Return a default username value from tool_provider in case offical
+        LTI param lis_person_sourcedid was not present.
+        """
+        # Default back to user_id lti param
+        uname = tool_provider.get_custom_param('canvas_user_id') or tool_provider.user_id
+        return prefix + uname