old_contents: # -*- coding: utf-8 -*-
  from __future__ import unicode_literals
  
  from django.contrib import admin
  
  from .models import ExtraInfo
  
  admin.site.register(ExtraInfo)
  
new_contents: # -*- coding: utf-8 -*-
  from __future__ import unicode_literals
  
  from django.contrib import admin
  
  from .models import ExtraInfo
  
  class ExtraInfoAdmin(admin.ModelAdmin):
      """ Admin interface for ExtraInfo model. """
      list_display = ('user', 'get_email', 'last_name', 'first_name',)
      search_fields = ('user__username', 'user__email', 'last_name', 'first_name',)
  
      def get_email(self, obj):
          return obj.user.email
      get_email.short_description = 'Email address'
  
      class Meta(object):
          model = ExtraInfo
  
  admin.site.register(ExtraInfo, ExtraInfoAdmin)
  
subject: Change `ExtraInfo` to user fields, add search