python - 为什么我的应用引擎查询找不到我的实例？

Question

我一直在玩 App Engine，但我似乎误解了 NDB 数据存储查询。我将抛出的错误放在查询旁边。

在交互式控制台中玩耍:

from google.appengine.ext import ndb  

class Client(ndb.Model):  
    email =  ndb.StringProperty()  
    name = ndb.StringProperty(indexed=True)  

#instantiated client instance with the parameters below. ID is 6578378068983808  
#client = Client(email = "bryan@gmail.com", name = "Bryan Wheelock" ).put()  

client = Client.query( Client.name == 'Bryan Wheelock')  
#client = Client.query( Client.ID == 6578378068983808 ) #AttributeError: type object 'Client' has no attribute 'ID'  
#client = Client.all() #AttributeError: type object 'Client' has no attribute 'all'    
#client = Client.get_by_id(6578378068983808) #THIS WORKS returns u'Bryan Wheelock'   

pprint.pprint(client.name)  

我所做的示例查询直接来自 App Engine 文档，我做错了什么？

Answer 1

查询

Client.query() 返回一个查询对象。

您需要像这样从中获取结果:

query = Client.query( Client.name == 'Bryan Wheelock')
client = query.get() # first result

pprint.pprint(client.name)

或者只是:

client = Client.query( Client.name == 'Bryan Wheelock').get()
pprint.pprint(client.name)

编号

id 不是模型的属性，而是它的键的属性。要通过其 ID 直接获取客户端，您可以执行一个

client = Client.get_by_id(id)

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供您引用，您可以在此处查找模型方法:https://cloud.google.com/appengine/docs/python/ndb/modelclass