gistfile1.py

from django.db import models


class Entry(models.Model):

    title = models.CharField()
    active = models.BooleanField()

    def __init__(self, *args, **kwargs):
        super(Entry, self).__init__(*args, **kwargs)

        # Save field state
        self.__active = self.active
        
    def save(self, **kwargs):
        super(Entry, self).save(**kwargs)

        if not self.__active == self.active:
            # Do some works
            # ...