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djangodjango-signals

How to use update_fields in Django signals

I'm trying to use an the 'update_fields' argument passed to signals in Django.

I've got something very simple for now, namely:

@receiver(pre_save, sender=models.UserAdmin)
@receiver(pre_save, sender=models.UserGroupAdmin)
def update_timestamps(sender, instance, update_fields, **kwargs):
    print(f'Update fields: {update_fields}')

update_fields shows as None no matter what is being updated, which indicates I've not understood something.

What am I missing?

Solution

  • update_fields The set of fields to update as passed to Model.save(), or None if update_fields wasn’t passed to save().

    update_fields just pass up fields that you have in set in save() method for update

    They are not fields that are updated in particular case ( you could set few fields in this list but maybe only one of them will actually change in database)