django - Data is not being read directly from the database instead of buffer on 2nd call

Question

I have the following piece of code in my model that ensures that user will be not able to modify a record that was modified by someone else after he has opened it.

 def save(self, *args, **kwargs):
        on_disk = Lease.objects.get(pk=self.id)
        self.full_clean()
        if on_disk.version == self.version:
            error = 0 #do nothing
        else:
            raise ValidationError('Record have been modified by another user, please reopen and edit again')
        # self.version = self.version + 1 
        return super(Lease, self).save(*args, **kwargs)

There is mechanism implemented(Django concurrency package) that ensures that after each save version value will be modified.

However, this piece of code doesn't work it appears to me that on_disk value is not being populated with the most recent value from the disc but get it from some buffer and as result this code check is useless.

Any idea how to make it work?

Answer 1

Waitting for answers