old_contents: from django.contrib import admin
  from roaster.models import Cafe, Roaster, Roast
  
  class CafeAdmin(admin.ModelAdmin):
      prepopulated_fields = {'slug': ('name',)}
      list_display = ('name', 'address', 'phone', 'show_url', 'created_at', 'modified_at',)
      search_fields = ('name',)
  
      def show_url(self, obj):
          return '<a href="%s">%s</a>' % (obj.url, obj.url)
      show_url.allow_tags = True
      show_url.admin_order_field = 'url'
      show_url.short_description = 'URL'
  
  class RoasterAdmin(admin.ModelAdmin):
      prepopulated_fields = {'slug': ('name',)}
      list_display = ('name', 'address', 'phone', 'show_url', 'created_at', 'modified_at',)
      search_fields = ('name',)
  
      def show_url(self, obj):
          return '<a href="%s">%s</a>' % (obj.url, obj.url)
      show_url.allow_tags = True
      show_url.admin_order_field = 'url'
      show_url.short_description = 'URL'
  
  class RoastAdmin(admin.ModelAdmin):
      list_display = ('name', 'created_at', 'modified_at',)
      search_fields = ('name',)
  
  admin.site.register(Cafe, CafeAdmin)
  admin.site.register(Roaster, RoasterAdmin)
  admin.site.register(Roast, RoastAdmin)
  
new_contents: from django.contrib import admin
  from roaster.models import Cafe, Roaster, Roast
  
  class CafeAdmin(admin.ModelAdmin):
      prepopulated_fields = {'slug': ('name',)}
      list_display = ('name', 'address', 'phone', 'show_url', 'created_at',
              'modified_at', 'active',)
      search_fields = ('name',)
  
      def show_url(self, obj):
          return '<a href="%s">%s</a>' % (obj.url, obj.url)
      show_url.allow_tags = True
      show_url.admin_order_field = 'url'
      show_url.short_description = 'URL'
  
  class RoasterAdmin(admin.ModelAdmin):
      prepopulated_fields = {'slug': ('name',)}
      list_display = ('name', 'address', 'phone', 'show_url', 'created_at',
              'modified_at', 'active',)
      search_fields = ('name',)
  
      def show_url(self, obj):
          return '<a href="%s">%s</a>' % (obj.url, obj.url)
      show_url.allow_tags = True
      show_url.admin_order_field = 'url'
      show_url.short_description = 'URL'
  
  class RoastAdmin(admin.ModelAdmin):
      list_display = ('name', 'created_at', 'modified_at', 'active',)
      search_fields = ('name',)
  
  admin.site.register(Cafe, CafeAdmin)
  admin.site.register(Roaster, RoasterAdmin)
  admin.site.register(Roast, RoastAdmin)
  
subject: Add the active field to the model admin list.