Comparing 2 model entities

Is there an easy way to compare to entities to to check for property value differences? I want something like this:

me = User.get_by_id( 28 )
cloned_me = me

cloned_me.first_name = 'Tom'

if me != cloned_me:
 开发者_运维百科   self.response.out.write( 'These 2 objects have different property values' )

For simplest scenario you can compare objects field by field e.g.

from django.contrib.auth.models import User

def compare(user1, user2):
    for field in user1._meta.fields: 
        val1 = getattr(user1, field.name)
        val2 = getattr(user2, field.name)
        if val1 != val2:
            print "%s differ '%s' != '%s'"%(field.name, val1, val2)
            break

compare(User(username="anurag"), User(username="uniyal"))

output:

username differ 'anurag' != 'uniyal'

You can later on improve it if you need to further compare foerign keys etc

and i think you are aware that in your example clone_me is not actually a clone of me, it is me

Try using sets:

differences = set(me.__dict__) ^ set(cloned_me.__dict__)
if differences:
    self.response.out.write('These 2 objects have different property values')

You could even output the attributes that were different (they're contained in the new differences set).