Question

I am creating a “What’s New” section that lists all of the database changes in the last day. Off of a recent suggestion, I want use post_save or pre_save to capture the fields that have been altered when Django saves a model record. I will save this data in another table (time-stamped). I know this is possible because one can observe the behavior in the admin application – it identifies which fields have been altered).

As best I can tell, the admin application utilizes forms.changed_data. But using post_save or pre_save does not receive any forms information.

Is there an efficient way to determine which fields have been changed? Do I have to compare each field in the model to it’s current value (pre_save) to determine this list? Any help (with code examples) would be greatly appreciated.

Answer 1

There is an answer here. Basically you could cache your fields when initializing the object, and then in the post_save signal you can compare every field with the cached value … or write a method that does the comparison, and only returns the fields that have been modified.