old_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)
  
new_contents: # -*- coding: utf-8 -*-
  from __future__ import unicode_literals
  
  from django.contrib import admin
  from django.contrib.auth.admin import UserAdmin
  from django.contrib.auth.models import User
  from django.utils.html import format_html
  
  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
  
  
  class NewUserAdmin(UserAdmin):
      """
      Modifies admin interface for User model to display additional ExtraInfo link.
      """
      list_display = (
          'username',
          'email',
          'first_name',
          'last_name',
          'is_staff',
          'has_extra_info',
      )
  
      def has_extra_info(self, obj):
          if hasattr(obj, 'extrainfo'):
              return format_html(
                  '<a href="/admin/register_cme/extrainfo/{extrainfo_id}">ExtraInfo</a>',
                  extrainfo_id=obj.extrainfo.id,
              )
          else:
              return ''
      has_extra_info.short_description = 'ExtraInfo'
      has_extra_info.allow_tags = True
  
  admin.site.register(ExtraInfo, ExtraInfoAdmin)
  admin.site.unregister(User)
  admin.site.register(User, NewUserAdmin)
  
subject: Add extraInfo link in `/admin/auth/user`