ValueError is preventing me from migrating in Django

Question

I'm very new to Django and am primarily working through tutorials. I was attempting to create a model that has an author field. At a certain point when I was going through a migration process and used makemigrations, I received a series of messages in the console stating that I needed to set up default values for many of my fields in my models. So for author I put default='someauthor'.

I later removed these defaults, still confused as to why that happened. I then went through the 'makemigrations' again and those messages were no longer prompting me. I forget what I did to change that.

However when I try to migrate 'python manage.py migrate' I get this error:

ValueError: invalid literal for int() with base 10: 'someauthor'

I've removed all references to "default='someauthor'" but this error remains. I will add that I have two models each of which make a reference to an author:

author = models.ForeignKey(User, related_name='tutorial_posts')

and

author = models.ForeignKey(User, related_name='blog_posts')

I feel like that has caused the problem. Any suggestions?

AKS · Accepted Answer · 2016-05-07 04:15:46Z

ForeignKey field stores the id from the other table which is by default an int. If you add a default value as string it won't be able to convert it to int and provide you this error:

ValueError: invalid literal for int() with base 10: 'someauthor'

You can check this yourself by trying this in a console:

In [3]: int('someauthor') --------------------------------------------------------------------------- ValueError Traceback (most recent call last) <ipython-input-3-3c4d496afcf9> in <module>() ----> 1 int('someauthor') ValueError: invalid literal for int() with base 10: 'someauthor'

What I suggest is that either you use an int value for default or set null=True:

author = models.ForeignKey(User, related_name='blog_posts', null=True)

Okay, so even though I removed it, it still assumes the string is the default?
I think your migration files might have the value from the older model state. Please check that , delete those migrations and run makemigrations again.
Thanks. Now I'll try to figure out the process of removing tables from the database. So far it's not going well.

KLazman · Accepted Answer · 2019-12-23 03:28:46Z

I had the same issue and could not proceed with any other migrations

I was able to resolve by searching in the project directory for the string passed as the default value, in your case 'someauthor'

You should be able to find in the migrations folder a .py migration file.

` from django.conf import settings from django.db import migrations, models import django.db.models.deletion class Migration(migrations.Migration): dependencies = [ migrations.swappable_dependency(settings.AUTH_USER_MODEL), ('accounts', '0004_auto_20191221_2233'), ] operations = [ migrations.RemoveField( model_name='useraccount', name='username', ), migrations.AddField( model_name='useraccount', name='user', field=models.ForeignKey(default='string', on_delete=django.db.models.deletion.CASCADE, to=settings.AUTH_USER_MODEL), preserve_default=False, ), ]`

Change the default='string' to 1

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