auto_now and auto_add_now are attributes to Django DateTimeField methods.

auto_now changes the field to timezone.now whenever the field is saved, auto_now_add on the other hand only updates the field once when it is created.

Let’s say you have created a model like this:

class TimeTest(models.Model):
    created = models.DateTimeField(auto_now_add=True)
    updated = models.DateTimeField(auto_now=True)

Now, for some reasons, you want to update the created field in your model - You Can’t.

So you think, what can I do, you do some googling, and find that there’s a property called editable.

So you set created.editable = True, and voila it works. In your Django Admin panel the created field is now editable.

What’s the problem then?

Addressing the Issue

When you try to update the model, and rerun the makemigration or migrate commands, you get an error saying

    del kwargs['editable']
KeyError: 'editable'

This is because you can’t make the DateTimeField editable in the model, so when you try to makemigrate your model, python throws tantrums.

In my opinion, this has been done to prevent accident changes to data that are supposed to store the DateTime of object creation. However, you can change this time - after migrating your models, you can just change the field to be editable,

# Uncomment for testing purposes only
# Causes key error while migration because auto_now_add is uneditable by default
created.editable = True

Then you can change the fields now. When you’re done you can change the model back to its original state.

A Better Solution?

When you encounter this problem, you may want to rethink whether you truly want the field to have auto_now_add as well as editable=True. If the answer is no, then great, fix your model.

If yes, then you need some workaround. One of the most common ways is to entirely avoid auto_now_add and instead pass the time of object creation explicitly. This way you can control the time easily. Another solution is to create a new data type that inherits from Django DataTimeField and modify as per your needs as discussed here https://stackoverflow.com/a/1737078/4748060.