old_contents: from django.contrib import admin
  
  from models import *
  
  class MessageAdmin(admin.ModelAdmin):
      readonly_fields = ['subscription', 'time_recorded', 'topic', 'payload']
  
  admin.site.register(MQTTMessage, MessageAdmin)
  
  admin.site.register(MQTTSubscription)
  
new_contents: from django.contrib import admin
  
  from models import *
  
  class MessageAdmin(admin.ModelAdmin):
      readonly_fields = ('subscription', 'time_recorded', 'topic', 'payload')
      date_hierarchy = 'time_recorded'
      list_display = ('time_recorded', 'subscription', 'topic', 'payload')
      list_display_links = ('payload',)
      list_filter = ('subscription', 'time_recorded', 'topic')
      ordering = ('-time_recorded',)
  
  admin.site.register(MQTTMessage, MessageAdmin)
  
  class SubscriptionAdmin(admin.ModelAdmin):
      list_display = ('server', 'topic', 'active')
      list_editable = ('active',)
      list_filter = ('server', 'active')
      ordering = ('server', 'topic')
  
  admin.site.register(MQTTSubscription, SubscriptionAdmin)
  
subject: Improve list displays in admin interface.