Django snippets

from django.db.models import CharField

try:
    import uuid
except ImportError:
    from django.utils import uuid


class UUIDField(CharField) :
    
    def __init__(self, *args, **kwargs):
        kwargs['max_length'] = kwargs.get('max_length', 32 )
        CharField.__init__(self, *args, **kwargs)
    
    def pre_save(self, model_instance, add):
        if add :
            value=getattr(model_instance,self.attname)
            if not value:
                value = unicode(uuid.uuid4()).replace('-','')
            setattr(model_instance, self.attname, value)
            return value
        else:
            return super(CharField, self).pre_save(model_instance, add)