以编程方式从GAE数据存储区中的Message创建具有ReferenceProperty的实体

I'd like to be able to automatically insert an entity with a reference t another entity directly from a message, using Google Endpoints.

我希望能够使用Google端点直接从邮件中自动插入带有引用另一个实体的实体。

To transmit ReferenceProperty in message, I use the encoded string value of the Key. That is fine for sending message, but when receiving message, and creating an entity of it, I cannot just pass the encoded string as a parameter to the constructor.

要在消息中传输ReferenceProperty，我使用Key的编码字符串值。这对于发送消息很好，但是当接收消息并创建它的实体时，我不能只将编码的字符串作为参数传递给构造函数。

For instance, say I have two classes that inherits from BaseModel which itself inherits from db.models

例如，假设我有两个继承自BaseModel的类，它本身继承自db.models

class TestModel2(models.BaseModel):
    test_string = db.StringProperty(required=True)

class TestModel(models.BaseModel):
    test2 = db.ReferenceProperty(TestModel2)
    test2_id = property(models.BaseModel._get_attr_id_builder('test2'),
                       models.BaseModel._set_attr_id_builder('test2'))

And a message class

还有一个消息类

class TestModelMessage(messages.Message):
    test2_id = messages.StringField(4)

I want to be able to create an Entity TestModel directly of the TestModelMessage.

我希望能够直接创建TestModelMessage的Entity TestModel。

I managed to do it in the other way (from to entity to message) using a property. But in the other way it doesn't work since I have the feeling that the constructor for db.models will only set the attributes that inherits db.Property. Thus the setter for the property won't be called...

我设法使用属性以另一种方式（从实体到消息）执行此操作。但另一方面它不起作用，因为我觉得db.models的构造函数只会设置继承db.Property的属性。因此，不会调用属性的setter ...

How could I do this?

我怎么能这样做？

I thought of overriding the __init__ in BaseModel but then when calling the __init__ of db.models it will probably override the ReferenceProperty.

我想过覆盖BaseModel中的__init__，但是当调用db.models的__init__时，它可能会覆盖ReferenceProperty。

1 个解决方案

#1

So, I added a _ref_properties field to the BaseModel class. For the previous example, it would be _ref_properties = {'test2': 'test2_id'}

所以，我在BaseModel类中添加了一个_ref_properties字段。对于前面的示例，它将是_ref_properties = {'test2'：'test2_id'}

Then I added this class method

然后我添加了这个类方法

@classmethod
def from_message(cls, message, *args):
    attributes = {attr: getattr(message, attr) for attr in args}
    for attribute, property in cls._ref_properties.items():
        attributes[attribute] = db.Key(encoded=getattr(message, property))
    entity = cls(**attributes)
    return entity

And it seems to work. Probably not the best. Any remarks or better solution?

它似乎工作。可能不是最好的。任何言论或更好的解决方案？

#1