track Django models values changes.

models.py

from django.db import models
from django.db.models.signals import pre_save, post_init

def track_model_changes(sender, instance, **kwargs):
    """Save former data to compare with new data and track changed values"""
    instance.__former = dict((field.name, field.value_from_object(instance)) for field in Report._meta.fields)




class Example(models.Model):
  status = models.IntegerField()

post_init.connect(track_model_changes, sender=Example)

@receiver(pre_save, sender=Example)
def check_status(sender, instance, **kwargs):
    if report.__former['status'] != report.status:
        print "status changed"