taggable mixin

近日，google app engine推出了open source projects，已有近20个项目加入。taggable-mixin也是其中之一，由Adam Crossland主持维护。

Taggable 是一个Python mixin class，可以添加在任何从google app engine db.Model 继承的类中。taggable主要通过get_tags_as_string、set_tags和set_tags_from_string等方法实现对 tag的存取。以下是我对taggable进行的尝试：

在使用taggable前，首先把 taggable.py 复制到您的application目录。

Model

from google.appengine.ext import db
import taggable

class shop(db.Model, taggable.Taggable):
owner = db.UserProperty(required=True)
name = db.StringProperty(required=True)
slug = db.StringProperty(required=True)
logo = db.BlobProperty()
description = db.TextProperty()
created = db.DateTimeProperty(auto_now_add=True)

def __init__(self, parent=None, key_name=None, app=None, **entity_values):
  db.Model.__init__(self, parent, key_name, app, **entity_values)
  taggable.Taggable.__init__(self)

View

class MyShop(BaseHandler):
@requires_login
def get(self):
 shop = Shop.all().filter('owner = ', self.user).get()
 if shop:
   shop.get_tags_as_string()

 self.template_values.update({
   'shop': shop,
   })
 self.render('shop.html')

@requires_login
def post(self):
 name = self.request.get('name')
 slug = self.request.get('slug').strip().lower()
 description = self.param('description')
 logo = db.Blob(images.resize(self.param('logo'),128,128))

 shop = Shop.all().filter('owner = ', self.user).get()
 if not shop:
   shop = Shop(owner = self.user,
               name = name,
               slug = slug,
               description = description,
               logo = logo,
               )
 else:
   shop.name = name
   shop.slug = slug
   shop.description = description
   if logo:
     shop.logo = logo
 shop.put()

 if (strip(self.param('tags')) != None):
   shop.set_tags_from_string(self.param('tags'))

 self.redirect('/shop/' + slug)

Template

{% extends "base.html" %}

{% block title %}A taggable exmple{% endblock %}

{% block main %}
<h1>My shop</h1>

<form id="myShopForm" action="" method="post" enctype="multipart/form-data">
 Shop name: *<br />
 <input type="text" name="name" value="{{shop.name}}" />
 <br />Slug: *<br />
 <input type="text" name="slug" value="{{shop.slug}}" />
 <br />Description:<br />
 <textarea name="description" id="description" >{{shop.description|escape}}</textarea>
 <br />
 <img src="/showlogo/{{shop.slug}}" />
  <br />Logo:  (The picture will auto resize to 128 X 128px)<br />
  <input id="shoplogo" type="file" name="logo" accept="jpg|gif|png" />
 <p></p>
 <br />Tags: *<br />
 <input type="text" name="tags" value="{% for each_tag in shop.tags %}
       {{each_tag.tag}}{% if not forloop.last %}, {% endif %}{% endfor %}" />

 <input type="submit" value="Submit">
</form>
{% endblock %}

taggable提供了对tag操作的便利，有兴趣的朋友可以移步http://code.google.com/p/taggable-mixin/获得更多信息，源码包中有详细的帮助文件。
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