update episode cover

aircox/models/program.py

@@ -86,6 +86,7 @@ class Program(Page):
         super().__init__(*kargs, **kwargs)
         if self.slug:
             self.__initial_path = self.path
+            self.__initial_cover = self.cover
 
     @classmethod
     def get_from_path(cl, path):
@@ -133,6 +134,7 @@ class Program(Page):
 
         super().save(*kargs, **kwargs)
 
+        # TODO: move in signals
         path_ = getattr(self, '__initial_path', None)
         if path_ is not None and path_ != self.path and \
                 os.path.exists(path_) and not os.path.exists(self.path):

aircox/models/signals.py

@@ -56,6 +56,13 @@ def program_post_save(sender, instance, created, *args, **kwargs):
         Episode.object.parent(instance).filter(diffusion__isnull=True) \
                .delete()
 
+    cover_ = getattr(instance, '__initial_cover', None)
+    if cover_ is None and instance.cover is not None:
+        Episode.objects.parent(instance) \
+                       .filter(cover__isnull=True) \
+                       .update(cover=instance.cover)
+
+
 
 @receiver(signals.pre_save, sender=Schedule)
 def schedule_pre_save(sender, instance, *args, **kwargs):