old_contents: from django.contrib import admin
  from .models import Dinner, Order, Restaurant
  
  
  @admin.register(Restaurant)
  class RestaurantAdmin(admin.ModelAdmin):
      fieldsets = [
          ("Restaurant's name", {'fields': ['name']}),
          ("Phone's number:", {'fields': ['phone_number']}),
      ]
      search_fields = ['name']
  
  
  @admin.register(Dinner)
  class DinnerAdmin(admin.ModelAdmin):
      fieldsets = [
          (None, {'fields': ('name', 'price')}),
          ("Restaurant:", {'fields':  ["restaurant"]}),
          ('Description:', {'fields': ["description"]}),
      ]
      search_fields = ['name']
      radio_fields = {"restaurant": admin.VERTICAL}
      list_filter = (
          ('restaurant', admin.RelatedOnlyFieldListFilter),
      )
  
  
  @admin.register(Order)
  class OrderAdmin(admin.ModelAdmin):
      list_display = ("name", "add_date", "ordering_user", "ordered")
  
new_contents: from django.contrib import admin
  from .models import Dinner, Order, Restaurant
  
  
  @admin.register(Restaurant)
  class RestaurantAdmin(admin.ModelAdmin):
      fieldsets = [
          ("Restaurant's name", {'fields': ['name']}),
          ("Phone's number:", {'fields': ['phone_number']}),
      ]
      search_fields = ['name']
  
  
  @admin.register(Dinner)
  class DinnerAdmin(admin.ModelAdmin):
      fieldsets = [
          (None, {'fields': ('name', 'price')}),
          ("Restaurant:", {'fields':  ["restaurant"]}),
          ('Description:', {'fields': ["description"]}),
      ]
      search_fields = ['name']
      radio_fields = {"restaurant": admin.VERTICAL}
      list_filter = (
          ('restaurant', admin.RelatedOnlyFieldListFilter),
      )
  
  
  @admin.register(Order)
  class OrderAdmin(admin.ModelAdmin):
      list_display = ("name", "add_date", "ordering_user", "ordered")
      list_filter = (
          ('ordered', admin.BooleanFieldListFilter),
      )
  
subject: Add list_filter in admin.py class Order.