Update for ONLY changed fields

extend.py

from django.db import models

class ChangedOnlySaveModel(models.Model):
    def __init__(self, *args, **kwargs):
        models.Model.__init__(self, *args, **kwargs)
        self._initial_data = self.__dict__.copy()

    def save(self, commit=True):
        if not self.pk:
            models.Model.save(self, commit)
        else:
            changed = []
            for k, v in self._initial_data.iteritems():
                if (v != self.__dict__[k]) and (k != '_initial_data'):
                    changed.append((k, v))
            if len(changed) > 0:
                self.__class__.objects.filter(pk=self.pk).update(**dict(changed))
                self._initial_data = self.__dict__.copy()

    class Meta:
        abstract = True

main.py

from django.db import connection

class Post(ChangedOnlySaveModel):
    title = models.Charfield(max_length=100)
    content = models.TextField()

Post(title='title', content='content').save()

#

post = Post.objects.all()[0]
post.content = 'Hello World'
post.save()
print connection.queries

output.txt

[{'time': '0.001', 'sql': u'UPDATE "phone_post" SET "content" = content WHERE "phone_post"."id" = 1 '}]