old_contents: from django.contrib import admin
  
  from django_monitor.admin import MonitorAdmin
  
  from .models import GroundtruthRecord
  
  
  class GroundtruthRecordAdmin(MonitorAdmin):
      list_display = ('pk', 'use', 'contact_email', 'contact_phone', 'added',)
  
  
  admin.site.register(GroundtruthRecord, GroundtruthRecordAdmin)
  
new_contents: from django.contrib import admin
  
  from django_monitor.admin import MonitorAdmin
  
  from .models import GroundtruthRecord
  
  
  class GroundtruthRecordAdmin(MonitorAdmin):
      list_display = ('pk', 'use', 'address', 'contact_email', 'contact_phone',
                      'added',)
  
      def address(self, obj):
          try:
              return obj.content_object.address_line1
          except Exception:
              return ''
  
  
  admin.site.register(GroundtruthRecord, GroundtruthRecordAdmin)
  
subject: Address in admin