Null value in column "name" violates not-null constraint when adding new item in django admin

Question

I have added a new model to my admin. This is my models.py:

class EngineeringToolAttributeType(models.Model):
    name = models.CharField(max_length=50)
    description = models.CharField(max_length=255, blank=True, null=True)
    api_url = models.CharField(max_length=255, blank=True, null=True)
    api_field = models.CharField(max_length=50, blank=True, null=True)
    active = models.BooleanField(default=True)

    def __str__(self):
        return self.name

And the admin.py:

from extras.models import EngineeringToolAttributeType
from django.contrib import admin

class EngineeringToolAttributeTypeAdmin(admin.ModelAdmin):
    fields = ['name', 'description', 'api_url', 'api_field', 'active']
    list_display = ('name', 'description', 'api_url', 'api_field', 'active')

admin.site.register(EngineeringToolAttributeType, EngineeringToolAttributeTypeAdmin)

When I try to add (click on add button via the admin), I get this error:

Internal Server Error: /website/admin/extras/engineeringtoolattributetype/add/

IntegrityError at /admin/extras/engineeringtoolattributetype/add/
null value in column "name" violates not-null constraint

This has never happened before. I know name is not allowed to be Null, but I'm still adding a record. How is that possible?

Just to make sure, this is **before** you submit the form? Just clicking the "Add" button, so it should present you the form. — , Jun 27 '17 at 15:10
@JoshKopenI'm not trying to add any record yet. I clicked on button "Add" to bring me to the form. — Ruben, Jun 27 '17 at 20:51
@FazilZaid yes, it looks the problem is with fields called "name", because I have the same problem with other models. More a PostgreSQL I think — Ruben, Jun 30 '17 at 06:58
I have just ran the code in my machine and it works perfect. I too am using PostgreSQL. What's the version of your django? — zaidfazil, Jun 30 '17 at 07:01
Please include the full traceback. Do you get the same error if you remove your model's `__str__` method? — Alasdair, Jul 03 '17 at 12:06

score 13 · Answer 1 · answered Jul 03 '17 at 12:00

This issue is partially result of not using CharField and TextField properly. You should almost never use null=True on this fields and their subclasses. https://docs.djangoproject.com/en/1.11/ref/models/fields/#django.db.models.Field.null

Avoid using null on string-based fields such as CharField and TextField. If a string-based field has null=True, that means it has two possible values for “no data”: NULL, and the empty string. In most cases, it’s redundant to have two possible values for “no data;” the Django convention is to use the empty string, not NULL. One exception is when a CharField has both unique=True and blank=True set. In this situation, null=True is required to avoid unique constraint violations when saving multiple objects with blank values.

I would highly suggest removing this param from yourCharFields and TextFields.

Also just to be sure run ./manage.py makemigrations && ./manage.py migrate.

in fact, name is NOT NULL (you can see it in my model), which is ok, but I get the "null" problem anyways — Ruben, Jul 11 '17 at 09:12

score 3 · Accepted Answer · answered Jul 06 '17 at 06:41

This has a short answer here.
If you specify a field as not null field django will ask you to either provide a default value in code itself or it will ask you to provide a default value when you run migrations. A better approach would be to provide some sane default in your models.py itself. After that run python manage.py makemigrations and python manage.py migrate. You should be fine.

Null value in column "name" violates not-null constraint when adding new item in django admin

2 Answers2