Google App Engine：如何以编程方式访问Model类的属性？

I have a model class:

我有一个模型类:

class Person(db.Model):
  first_name = db.StringProperty(required=True)
  last_name = db.StringProperty(required=True)

I have an instance of this class in p, and string s contains the value 'first_name'. I would like to do something like:

我在p中有这个类的实例,而字符串s包含值'first_name'。我想做的事情如下:

print p[s]

and

p[s] = new_value

Both of which result in a TypeError.

两者都会导致TypeError。

Does anybody know how I can achieve what I would like?

有谁知道我怎么能达到我的意愿?

5 个解决方案

#1

If the model class is sufficiently intelligent, it should recognize the standard Python ways of doing this.

如果模型类足够智能,它应该识别标准的Python方法。

Try:

getattr(p, s)
setattr(p, s, new_value)

There is also hasattr available.

还有hasattr可用。

#2

With much thanks to Jim, the exact solution I was looking for is:

非常感谢Jim,我正在寻找的确切解决方案是:

p.properties()[s].get_value_for_datastore(p)

To all the other respondents, thank you for your help. I also would have expected the Model class to implement the python standard way of doing this, but for whatever reason, it doesn't.

致所有其他受访者,谢谢你的帮助。我也希望Model类能够实现python标准的方法,但无论出于何种原因,它都没有。

#3

getattr(p, s)
setattr(p, s, new_value)

#4

Try:

p.model_properties()[s].get_value_for_datastore(p)

See the documentation.

请参阅文档。

#5

p.first_name = "New first name" p.put()

p.first_name =“新名字”p.put()

or p = Person(first_name = "Firsty", last_name = "Lasty" ) p.put()

或者p = Person(first_name =“Firsty”,last_name =“Lasty”)p.put()