django-orm如何确保postgres数组字段不是空列表

Question

django有以下模型。该模型创建了一个名为metric_vals的数组字段，但它允许数组为空数组。有没有办法确保数组始终是非空数组？

from django.db import models
import uuid
from django.contrib.postgres.fields import ArrayField
class SampleModel(models.Model):
id = models.UUIDField(primary_key=True, default=uuid.uuid4, editable=False)
metric_vals = ArrayField(models.FloatField(null=False), null=False, default=list)

Answer 1

您可以使用validatorskwarg:

from django.contrib.postgres.validators import ArrayMaxLengthValidator, ArrayMinLengthValidator

def get_default_list():
return [float(1), float(2)]
class SampleModel(models.Model):
metric_vals = ArrayField(
models.FloatField(null=False), 
null=False, 
# ensure the default passes the validation
default=get_default_list,
# like this
validators=[
ArrayMinLengthValidator(2),
ArrayMaxLengthValidator(10),
]
)

相关：

• https://docs.djangoproject.com/en/4.1/ref/validators/

Answer 2

类似这样的东西：

from django.core.exceptions import ValidationError
class SampleModel(models.Model):
id = models.UUIDField(primary_key=True, default=uuid.uuid4, editable=False)
metric_vals = ArrayField(models.FloatField(null=False), null=False, default=list)
def save(self, *args, **kwargs):
if self.metric_vals == []:
raise ValidationError('Empty list not allowed')
super().save(*args, **kwargs)