Python Django 将整数模型字段的范围设置为约束
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Django set range for integer model field as constraint
提问by Md. Tanvir Raihan
I have a django model,
我有一个 Django 模型，
class MyModel(models.Model)
qty = model.IntegerField()
where I want to set constraint for qtysomething like this, >0 or <0,i.e the qtycan be negative or positive but can not be 0.
我想为qty这样的东西设置约束，>0 或 <0，即qty可以是负数或正数，但不能是 0。
Is there any straight forward way to do this in Django?
在 Django 中有什么直接的方法可以做到这一点吗？
采纳答案by JRodDynamite
You can use Django's built-in validators-
您可以使用Django 的内置验证器-
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 linkfor more info.
注意：当您保存模型时，验证器不会自动运行，但如果您使用的是 ModelForm，它将在表单中包含的字段上运行您的验证器。查看此链接以获取更多信息。
回答by utkbansal
You will have to create a custom validator
您将不得不创建一个自定义验证器
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
然后在你的模型中使用这个验证器
from django.db import models
class MyModel(models.Model):
field = models.IntegerField(validators=[validate_number])
回答by Kishan
If you are using postgres, you can use range fields to specify the range. Check this: Range Fields in django
如果您使用的是 postgres，则可以使用范围字段来指定范围。检查这个：Django 中的范围字段
回答by maerteijn
Since Django 2.2 you can enforce the constraints on a database level with CheckConstraint:
从 Django 2.2 开始，您可以使用CheckConstraint在数据库级别强制执行约束：
from django.db import models
class MyModel(models.Model)
qty = model.IntegerField()
class Meta:
constraints = [
models.CheckConstraint(
check=models.Q(qty__gte=1) & models.Q(qt__lte=10),
name="A qty value is valid between 1 and 10",
)
]
