Django set range for integer model field as constraint
You will have to create a custom validator
from django.core.exceptions import ValidationError
def validate_number(value):
if something : # Your conditions here
raise ValidationError('%s some error message' % value)
And then use this validator in your model
from django.db import models
class MyModel(models.Model):
field = models.IntegerField(validators=[validate_number])
You can use Django's built-in validators -
from django.db import models
from django.core.validators import MaxValueValidator, MinValueValidator
class MyModel(models.Model):
qty = models.IntegerField(
default=1,
validators=[MaxValueValidator(100), MinValueValidator(1)]
)
NOTE:
- The validators will not run automatically when you save a model, but if you are using a ModelForm, it will run your validators on the fields that are included in the form. Check this link for more info.
- To enforce constraints on a database level refer to maertejin's answer below.
Since Django 2.2 you can enforce the constraints on a database level with CheckConstraint:
class MyModel(models.Model):
qty = models.IntegerField()
class Meta:
constraints = [
models.CheckConstraint(
check=models.Q(qty__gte=1) & models.Q(qty__lt=10),
name="A qty value is valid between 1 and 10",
)
]