When editing tags in admin, add their parents as in a thread creation form

boards/admin.py

@@ -1,75 +1,84 b''
 from django.contrib import admin
 from boards.models import Post, Tag, Ban, Thread, Banner
 from django.utils.translation import ugettext_lazy as _
 
 
 @admin.register(Post)
 class PostAdmin(admin.ModelAdmin):
 
     list_display = ('id', 'title', 'text', 'poster_ip')
     list_filter = ('pub_time',)
     search_fields = ('id', 'title', 'text', 'poster_ip')
     exclude = ('referenced_posts', 'refmap')
     readonly_fields = ('poster_ip', 'threads', 'thread', 'images',
             'attachments', 'uid', 'url', 'pub_time', 'opening')
 
     def ban_poster(self, request, queryset):
         bans = 0
         for post in queryset:
             poster_ip = post.poster_ip
             ban, created = Ban.objects.get_or_create(ip=poster_ip)
             if created:
                 bans += 1
         self.message_user(request, _('{} posters were banned').format(bans))
 
     actions = ['ban_poster']
 
 
 @admin.register(Tag)
 class TagAdmin(admin.ModelAdmin):
 
     def thread_count(self, obj: Tag) -> int:
         return obj.get_thread_count()
 
     def display_children(self, obj: Tag):
         return ', '.join([str(child) for child in obj.get_children().all()])
 
     list_display = ('name', 'thread_count', 'display_children')
     search_fields = ('name',)
 
 
 @admin.register(Thread)
 class ThreadAdmin(admin.ModelAdmin):
 
     def title(self, obj: Thread) -> str:
         return obj.get_opening_post().get_title()
 
     def reply_count(self, obj: Thread) -> int:
         return obj.get_reply_count()
 
     def ip(self, obj: Thread):
         return obj.get_opening_post().poster_ip
 
     def display_tags(self, obj: Thread):
         return ', '.join([str(tag) for tag in obj.get_tags().all()])
 
     def op(self, obj: Thread):
         return obj.get_opening_post_id()
 
+    # Save parent tags when editing tags
+    def save_related(self, request, form, formsets, change):
+        super().save_related(request, form, formsets, change)
+        obj = form.instance
+        for tag in obj.get_tags().all():
+            parents = tag.get_all_parents()
+            if len(parents) > 0:
+                obj.tags.add(*parents)
+
     list_display = ('id', 'op', 'title', 'reply_count', 'status', 'ip',
             'display_tags')
     list_filter = ('bump_time', 'status')
     search_fields = ('id', 'title')
     filter_horizontal = ('tags',)
 
 
 @admin.register(Ban)
 class BanAdmin(admin.ModelAdmin):
     list_display = ('ip', 'can_read')
     list_filter = ('can_read',)
     search_fields = ('ip',)
 
 
 @admin.register(Banner)
 class BannerAdmin(admin.ModelAdmin):
     list_display = ('title', 'text')