本文介绍了Google App Engine数据存储模型参考另一个类的处理方法,对大家解决问题具有一定的参考价值,需要的朋友们下面随着小编来一起学习吧!
问题描述
为了能够理解数据模型,我基本上都有城市,在每个城市中我会有类别,然后在每个类别中我都有列表。这是我目前所拥有的。 from google.appengine.ext import db
class City( db.Model):
name = db.StringProperty(required = True)
connections = db.ListProperty()
categories = db.ListProperty()
所以接下来,我想添加:
class Category(db.Model)
name = db.StringProperty(required = True)
但是,我是否需要指定只有类别应该在类别或类似的情况下才能生效?
您的 City
中的类别
属性,并使用 ReferenceProperty
您的类别
class:
class Category(db.Model)
name = db.StringProperty(required = True)
city = db.ReferenceProperty(City,collection_name ='categories')
这也会自动完成为城市
模型添加类别
集合。
So that you can understand the data model, I basically have cities and within each one I'll have categories and then inside each category I'll have listings. Here's what I have so far.
from google.appengine.ext import db
class City(db.Model):
name = db.StringProperty(required=True)
connections = db.ListProperty()
categories = db.ListProperty()
So Next, I want to add:
class Category(db.Model)
name = db.StringProperty(required=True)
But do I need to specify that only Category should be in categories or something to that effect?
解决方案
You need to throw the categories
property from your City
and use a ReferenceProperty
in your Category
class:
class Category(db.Model)
name = db.StringProperty(required=True)
city = db.ReferenceProperty(City, collection_name = 'categories')
This will also automatically add categories
collection for your City
model.
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