How can you create a non-empty CharField in Django?

Question

I have a simple model which looks like this:

class Group(models.Model):
    name = models.CharField(max_length = 100, blank=False)

I would

Answer 1

another option that doesn't require you to manually call clean is to use this:

name = models.CharField(max_length=100, blank=False, default=None)

• blank will prevent an empty string to be provided in your model
• default=None will set name to None when using something like group = Group(), thus raising an exception when calling save

Answer 2

I spent a long time looking for the best solution for this simple (and old) problem, And as of Django 2.2, there is actually a really simple answer, so I'll write it here in case someone still encounters the same problem:

Since Django 2.2, we can define CheckConstraints, so it's easy to define a non-empty string constraint:

from django.db import models

class Article(models.Model):
   title = models.CharField(max_length=32)

    class Meta:
        constraints = [
            models.CheckConstraint(check=~models.Q(title=""), name="non_empty_title")
        ]

Answer 3

Or you can simply use MinLengthValidator with a 1-char minimum:

from django.core.validators import MinLengthValidator

class Company(BaseModel):
    """Company"""

    name = models.CharField(max_length=255,
                            validators=[MinLengthValidator(1)])

Answer 4

From the Django docs in this case, your name will be stored as an empty string, because the null field option is False by default. if you want to define a custom default value, use the default field option.

name = models.CharField(max_length=100, blank=False, default='somevalue')

On this page, you can see that the blank is not database-related.

Update:

You should override the clean function of your model, to have custom validation, so your model def will be:

class Group(models.Model):
  name = models.CharField(max_length=100, blank=False)
  def clean(self):
    from django.core.exceptions import ValidationError
    if self.name == '':
        raise ValidationError('Empty error message')

Or you can replace ValidationError to something else. Then before you call group.save() call group.full_clean() which will call clean()

Other validation related things are here.

Answer 5

Django’s validation system assumes that all fields are required,unless you mention that its ok to leave it blank..

Have you registered the class in Admin ? does it show errors when you leave it blank ??