add NoneType handler

Author: LeonardBongard

base/models/content.py

@@ -169,7 +169,10 @@ def get_rate_num(self):
         return self.get_rate()
 
     def get_rate(self):
-        return Rating.objects.filter(content_id=self.id).aggregate(Avg('rating'))['rating__avg']
+        rating = Rating.objects.filter(content_id=self.id).aggregate(Avg('rating'))['rating__avg']
+        if rating is not None:
+            return rating
+        return -1
 
     def get_rate_count(self):
         """

frontend/templates/frontend/course/topic_contents.html

@@ -26,7 +26,11 @@
                                 {% endfor %}
                             {% endif %}
                              · 
-                              <span class="badge badge-info">{{ content.get_rate}}</span>
+                            {% if content.get_rate == -1 %}
+                                <span class="badge badge-info"> ~ </span>
+                            {% else %}
+                                <span class="badge badge-info">{{ content.get_rate}}</span>
+                            {% endif %}
                         </div>
                     </div>
                 </div>