Djangoのadminのカスタマイズ例（search/sort/pagination)

admin.py

from django.contrib import admin
from .models import Memo

class MemoAdmin(admin.ModelAdmin):
    list_per_page = 5
    list_display = ['username', 'title']
    search_fields = ['user__username']

    def queryset(self, request):
        qs = super(MemoAdmin, self).queryset(request)
        qs = qs.select_related('user__username')
        return qs

    def username(self, obj):
        return obj.user.username
    username.admin_order_field = 'user__username'

admin.site.register(Memo, MemoAdmin)

models.py

from django.db import models
from django.contrib.auth.models import User

class Memo(models.Model):
    user = models.ForeignKey(User)
    title = models.CharField(max_length=128)
    body = models.TextField()

select_relatedで外部テーブルのカラムを予め指定することで、レコードごとにクエリ発行しないで済む