Python: How to get attribute of attribute of an object with getattr?

Question

How do I evaluate

a = myobject.id.number

and return None if it myobject is None

with built-in getattr? Maybe getattr(myobject, "id.number", None)?

Answer 1

getattr(getattr(myobject, "id", None), "number", None)

should work.

Answer 2

This should scale well to any depth:

reduce(lambda obj, attr : getattr(obj, attr, None), ("id","num"), myobject)

Answer 3

my favorites are

from functools import reduce
try:
  a = reduce(getattr, ("id", "number"), myobject)
except AttributeError:
  a = None

or

from operator import attrgetter
try:
  a = attrgetter('id.number')(myobject)
except AttributeError:
  a = None