You are trying to add a non-nullable field 'id' to contact_info without a default

Question

I am using the command python manage.py makemigrations

However, I get this error:

You are trying to add a non-nullable field 'id' to contact_info
without a default; we can't do that (the database needs something to
populate existing rows). 
Please select a fix: 
1) Provide a one-off default now (will be set on all existing rows) 
2) Quit, and let me add a default in models.py

Here is models.py:

class Document(models.Model):
    docfile = models.FileField(upload_to='documents/')


class contact_number(models.Model):
    contact_numbers = models.CharField(max_length=13)

class contact_address(models.Model):
    address = models.CharField(max_length=100)
    city = models.CharField(max_length=50)
    state = models.CharField(max_length=50)
    zip = models.CharField(max_length=5)

class contact_info(models.Model):
    first_name = models.CharField(max_length=50)
    last_name = models.CharField(max_length=50)
    email = models.EmailField()
    contact_numbers = models.ManyToManyField(contact_number)
    addresses = models.ManyToManyField(contact_address)

it's specific but i don't know how to correct this or put values in db. — shashank, Oct 07 '15 at 13:09
Did you have a different field set as the primary key before? I am surprised that the migration is trying to add an id field. — Alasdair, Oct 07 '15 at 13:38
If there isn't any important data in the database, then it might be easiest to drop the database and recreate it, delete any migrations for your app, then rerun `makemigrations`. — Alasdair, Oct 07 '15 at 14:37
i cleared the db, then restart syncdb but error still same :( — shashank, Oct 07 '15 at 14:55
Don't use syncdb, it's deprecated. Clear the database, delete any migrations, then recreate them. — Alasdair, Oct 08 '15 at 08:36
I had this issue when I forgot to clear out the old migration files AND changed from natural primary key to autoid. — roadrunner66, Sep 28 '19 at 00:02

score 70 · Accepted Answer · edited Sep 09 '19 at 07:23

70

This happens when a different field was marked as primary key with primary_key=True earlier and you are removing that (in case of which django tries to add an id primary key).

That Django is asking for a default value for a primary key seems to be a bug.

To work around this problem, follow these steps:

Supply a random default value when prompted during makemigrations.
Go to the migration file generated (under your_app\migrations\ and delete the default=x,, x being the random value you supplied in step 1.
While you are at the migration file, make sure the order of actions make sense (e.g., remove/alter one primary key before adding another). Save and close.
Migrate as usual.

edited Sep 09 '19 at 07:23

fedorqui

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answered May 20 '16 at 22:04

mehmet

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Yes that is the problem and the solution, it indeed is a bug it seems, the approved solution is not right. – Brambor Aug 05 '16 at 13:16
1

@mehmet Great! This workaround helped me move forward finally after trying many other things. It seems this is that bug (https://code.djangoproject.com/ticket/22997). But unfortunately, another bug (https://code.djangoproject.com/ticket/24030#comment:9) got exposed after doing the above. I had to delete the db entirely and rerun all the migrations to be able to use the default `id` field as the primary key. – Anupam Apr 12 '17 at 05:30

pycod333 · Answer 2 · 2015-10-16T09:52:30.673

26

you could set `default="" and also editable=False.

E.g first_name = models.CharField(max_length=50, default="", editable=False).

Adding id field is unnecessary. Django will add it automatically.

Edit: Deleting the last migration files in your migrations folder and retry again. If it doesn't work, repeat the same process, you will know you have deleted the right file when your "makemigrations" command works.

edited Oct 16 '15 at 09:52

answered Oct 07 '15 at 12:52

pycod333

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i didn't added id field. I want to migrate this model in to database but it showing those message which i don't know how to gone through this. – shashank Oct 07 '15 at 13:12
Have you ran the syncdb command first? run python manage.py makemigrations yourapp after running python manage.py syncdb – pycod333 Oct 07 '15 at 13:14
1

yup, it shows: No migrations to apply. Your models have changes that are not yet reflected in a migration, and so won't be applied. Run 'manage.py makemigrations' to make new migrations, and then rerun 'manage.py migrate' to apply them. – shashank Oct 07 '15 at 13:17
why don't you clear the db, then restart with syncdb. python manage.py flush – pycod333 Oct 07 '15 at 13:32
https://docs.djangoproject.com/en/1.8/topics/db/models/#automatic-primary-key-fields to override the id – pycod333 Oct 07 '15 at 18:17
1

The answer by mehmet solves the problem while this just do something else. "Adding id field is unnecessary. Django will add it automatically." well that is the problem, it seems that in Django 1.9 it doesnt. Happened to me as well. – Brambor Aug 05 '16 at 13:52

score 3 · Answer 3 · edited Oct 10 '15 at 12:37

3

You need to set a default value. For example:

field_eg = models.CharField(default="")

means:

name = models.CharField(max_length=100, default="")

edited Oct 10 '15 at 12:37

Drenmi

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answered Oct 10 '15 at 12:29

Anil Kumar Gupta

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score 3 · Answer 4 · edited Sep 07 '21 at 03:40

Check Your Migration Files

./manage.py showmigrations <App Name>

[X] 0001_initial

[X] 0002_auto_20181204_1110

Revert Your Migrations Using

./manage.py migrate <App Name> <migration file name>

Eg: 0001_initial.

Or use zero (for complete migration revert)

./manage.py migrate <App Name> zero

Check Your Migrations

./manage.py showmigrations <App Name>

[ ] 0001_initial

[ ] 0002_auto_20181204_1110

Now delete all revert migrations and migrate again.

./manage.py migrate <App Name>

score 1 · Answer 5 · answered Aug 01 '16 at 20:35

I ran into similar problem when doing makemigration. I had primary key with name 'Identity' and other fields in my models to which I applied makemigrations. Later, I changed primary key name to '_id' and I got this error.

You are trying to add a non-nullable field '_id' to swapidentity without a default; we can't do that (the database needs something to populate existing rows).

Error is bit misleading, but if you change back '_id' to 'Identity' you will not get that error.

How to fix? Delete migration script generated under migrations package. Or manually change primary key in your generated migration script.

I had a similar problem. I had a model, with a oneToOne field that was originally marked as a the primary key. I wanted to remove the primary key stuff and give it a default id. But there was a field on the model called "uid" and I was unable to follow @mehmet's procedure until i renamed the "uid" field to something without "id" in it. — Brett Elliot, Jan 07 '23 at 02:16

score 1 · Answer 6 · answered Nov 12 '18 at 18:09

In my opinion, completely deleting the migrations is a lazy and bad idea. I did a snafu similar to @Afiz Momin and was able to dig myself out.

I had the following setup:

A base abstract model.
Override the id field after creation (bad idea)
All other subclasses triggered Django migrations to try to create the ID field from the parent class.

So I would get the following every single time I ran makemigrations:

You are trying to add a non-nullable field 'id' to <tablename> without a default; we can't do that (the database needs something to populate existing rows).
Please select a fix:
1) Provide a one-off default now (will be set on all existing rows with a null value for this column)
2) Quit, and let me add a default in models.py

But there was a way out.

In my first attempt I would just seed a fake value in and then delete the created id column, but this was obviously unsustainable. But on a whim I did the following:

Backup the migrations directory to migrations.orig.
Run ./manage.py makemigrations to make all migrations.
Inspect the newly-created migrations file 0001-initial.

Chances are the model it's complaining about (<tablename>) is missing vital info. For me, it was missing the bases argument:

migrations.CreateModel(
    name='<ModelName>',
        fields=[
            ('id', models.AutoField(auto_created=True, primary_key=True, serialize=False, verbose_name='ID')),
            ('some_field', models.IntegerField()),
            # ... other fields ...
        ],
        options={
            'abstract': False,
        },
        bases=(<base_classes>),
    ),

Now go back to migrations.orig and search for the the migration where the model is first created. The migration line will look similar to the one above.
Once you find the line in migrations.orig, modify it to match the new migration code.
Restore your original migrations. Delete migrations and rename migrations.orig to migrations.
Just for good measure, run ./manage.py makemigrations and ./manage.py migrate. You should get no error messages anymore!
If it complains about another model, follow the same procedure described.

score 1 · Answer 7 · edited Nov 29 '20 at 15:21

1

you happen to be generating a relationship between tables, what you have to do is add a field null = True, in one of the fields of the tables that the error message is referring to (class contact_info).

edited Nov 29 '20 at 15:21

Montresor

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answered Nov 29 '20 at 15:09

AllisLove

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score 0 · Answer 8 · answered Oct 07 '15 at 12:47

0

This is happening because you have non-empty database. There must be line which has not been created through Django ORM.

Do the following: python manage.py shell

from <path_to_your_models> import *
print len(list(contact_info.objects.filter(id = None)))

This way you find out how many such rows are there. If you want to keep them just make migration script with some value that you give it to it.

answered Oct 07 '15 at 12:47

Jan Skácel

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i used shell and try to add the values in it but it shows : >>> p1 = contact_number(contact_numbers='12345678') >>> p1.save() IntegrityError: myapp_contact_number.contact_id_id may not be NULL How can i romove django default id or access myapp_contact_number.contact_id_id – shashank Oct 07 '15 at 13:55

score 0 · Answer 9 · answered Apr 10 '18 at 17:53

This can also happen if you made some changes in your models.py and tried migrating afterwards. Happened to me once. Deleting the entire database didn't help after all. In case the error is arriving after adding a Foreign Key, you cannot provide a default or it might be unsafe to set default as null.

Probably Django still has some of the previous migrations files in your myapp/migrations/ folder. Deleting those files might help.

score 0 · Answer 10 · answered Apr 19 '20 at 17:24

0

The database needs something to populate existing rows. So here you want to define some value for it you can use default=""

 contact_info = models.CharField(default="" ,max_length=15)

answered Apr 19 '20 at 17:24

Seth

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You are trying to add a non-nullable field 'id' to contact_info without a default

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