python - How do I reliably check if an attribute is defined for an object? -

sometimes create objects x attribute defined, don't.

class object(models.model):     x = models.integerfield(blank=true, null=true) 

i want create subset of objects x not defined @ point in app:

[o o in os if not hasattr(o,'x')] 

i've being playing around in shell, , don't results want.

>>> o = object() >>> o.save() >>> o.id 1l >>> hasattr(o,'x') true 

is checking x == none sufficient?

yes, checking x none sufficient.

any instance of object have attribute x, regardless of whether set - it'll none if didn't set it.