Add topic to objective admin view

server/objectives/admin.py

@@ -1,7 +1,8 @@
 from django.contrib import admin
+from wagtail.core.models import Page
 
 from objectives.models import ObjectiveGroup, Objective, ObjectiveProgressStatus
-
+from books.models import Topic
 
 @admin.register(ObjectiveGroup)
 class ObjectiveGroupAdmin(admin.ModelAdmin):
@@ -11,9 +12,31 @@ class ObjectiveGroupAdmin(admin.ModelAdmin):
 
 @admin.register(Objective)
 class ObjectiveAdmin(admin.ModelAdmin):
-    list_display = ('text', 'group', 'owner')
+    list_display = ('text', 'get_topic', 'group', 'owner')
     list_filter = ('group', 'owner')
 
+    def get_topic(self, obj):
+        try:
+            page = Page.objects.get(pk=obj.group.module.page_ptr_id)
+        except Page.DoesNotExist:
+            return None
+
+        parent_path = str(page.path)[:-4]
+
+        try:
+            parent = Page.objects.get(path=parent_path)
+        except Page.DoesNotExist:
+            return None
+
+        try:
+            topic = Topic.objects.get(page_ptr_id=parent.id)
+        except Topic.DoesNotExist:
+            return None
+
+        return topic.title
+
+    get_topic.short_description = 'Thema'
+
 
 @admin.register(ObjectiveProgressStatus)
 class ObjectiveProgressStatusAdmin(admin.ModelAdmin):