display feedback in admin backend

shiftregister/feedback/admin.py

@@ -1,3 +1,13 @@
 from django.contrib import admin
 
-# Register your models here.
+from .models import Feedback
+
+
+@admin.register(Feedback)
+class FeedbackAdmin(admin.ModelAdmin):
+    list_display = ("helper", "party", "next_year", "feedback_len")
+    readonly_fields = ("feedback_len",)
+    list_filter = ("party", "next_year")
+
+    def feedback_len(self, obj):
+        return len(obj.feedback_text)