old_contents: from django.contrib import admin
  
  from blog.models import Category, Post, Tag
  
  class PostAdmin(admin.ModelAdmin):
      model = Post
      readonly_fields = ['preview', ]
      fieldsets = (
          (None, {
              'fields': (('title', 'status'),
                         ('body', ),
                         ( 'preview', ),
                         ('category', 'tags'))
          }),
      )
      list_display = ['slug', 'created', 'modified']
  
  class CategoryAdmin(admin.ModelAdmin):
      model = Category
      exclude = ['slug', ]
  
  admin.site.register(Category, CategoryAdmin)
  admin.site.register(Post, PostAdmin)
  admin.site.register(Tag)
  
new_contents: from django.contrib import admin
  
  from blog.models import Category, Post, Tag
  
  class PostAdmin(admin.ModelAdmin):
      model = Post
      readonly_fields = ['preview', ]
      fieldsets = (
          (None, {
              'fields': (('title', 'status'),
                         ('body', ),
                         ( 'preview', ),
                         ('category', 'tags'))
          }),
      )
      list_display = ['title', 'created', 'modified', 'status']
      list_filter  = ['category', 'status']
      search_fields = ['title']
  
  class CategoryAdmin(admin.ModelAdmin):
      model = Category
      exclude = ['slug', ]
      list_display = ['name', 'parent']
  
  admin.site.register(Category, CategoryAdmin)
  admin.site.register(Post, PostAdmin)
  admin.site.register(Tag)
  
subject: Modify admin