Google App Engine: how can I programmatically access the properties of my Model class?

Question

I have a model class:

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:

print p[s]

and

p[s] = new_value

Both of which result in a TypeError.

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

Answer 1

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

Answer 2

Try:

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

See the documentation.

Answer 3

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

Try:

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

There is also hasattr available.

Answer 4

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

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.

Answer 5

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

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