Django models, adding new value, migrations

Question

I worked with django 1.9 and added a new field (creation_date) to myapp/models.py. After that I run "python manage.py makemigrations". I got:

Please select a fix:

Provide a one-off default now (will be set on all existing rows)

Quit, and let me add a default in models.py."

I choose 1-st option and added value in wrong format '10.07.2016'. After this mistake I couldn't run "python manage.py migrate".

So I decided to change models.py and add a default value "datetime.now". But after that I still have problems with "python manage.py makemigrations". I see such things like that:

django.core.exceptions.ValidationError: [u"'10.07.2016' value has an invalid format. It must be in YYYY-MM-DD HH:MM[:ss[.uuuuuu]][TZ] format."]

How to solve this problem?

edit your question to show the most recently generated migration. This can problably be fixed by editing that manually. — e4c5
– e4c5, Commented Sep 17, 2016 at 12:21
You need to amend your data before the second migration's run. I guess you can do an objects.update(creation_date=timezone.now()) on them, but if it didn't work, you can manually do it through your database's shell. — Ali
– Ali, Commented Sep 17, 2016 at 12:24

Roald Nefs · Accepted Answer · 2016-09-17 13:05:51Z

1

As long as your migration isn't applied to the database you can manually update your migration file located in myapp/migrations/*.py. Find the string '10.07.2016' and update it to a supported format.

A less attractive solution would be to delete the old migration file (as long as it isn't apllied to the database) and create a new migrations file with python manage.py makemigrations. Because you've updated the model to use a default value it won't ask for a one-off default this time.

To check whether a migration is applied to the database run: python manage.py showmigrations.

answered Sep 17, 2016 at 13:05

Roald Nefs

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