django - comparing old and new field value before saving

Question

I have a django model, and I need to compare old and new values of field BEFORE saving.

I\'ve tried the save() inheritence, and pre_save signal. It was triggered cor

Answer 1

Also you can use FieldTracker from django-model-utils for this:

1. Just add tracker field to your model:

   tracker = FieldTracker()
   

2. Now in pre_save and post_save you can use:

   instance.tracker.previous('modelfield')     # get the previous value
   instance.tracker.has_changed('modelfield')  # just check if it is changed