Django模型的限制条件确保一个或两个字段不是空字符串
遵循这个答案我想对Django模型设置约束，该模型确保设置了两个字段中的一个或两个。但是，尽管该答案假设空字段为null，但在我的情况下，它们总是是空字符串。我不确定如何在约束中检查一下。
from django.db import models
from django.db.models import Q
class Person(models.Model):
firstname = models.CharField(max_length=150, blank=True, null=False, default="")
surname = models.CharField(max_length=150, blank=True, null=False, default="")
class Meta:
constraints = [
models.CheckConstraint(
name="%(app_label)s_%(class)s_firstname_and_or_surname",
check=(
Q(firstname__exact="", surname__exact!="")
| Q(firstname__exact!="", surname__exact="")
| Q(firstname__exact!="", surname__exact!="")
),
)
]
这应该有效，除了surname_isnull = false，surname__exact！=“”不是有效语法。
我知道，如果我有一个QuerySet，我可以使用ubled（surname__exact =“”）表示“不是空”，但是我不确定如何在此约束中使用来做到这一点。 Q（）表达式。
Following this answer I want to set up a constraint on a Django model that ensures one or both of two fields are set. However, while that answer assumes the empty fields are NULL, in my case they are always empty strings. I'm not sure how to check for that in the constraint.
from django.db import models
from django.db.models import Q
class Person(models.Model):
firstname = models.CharField(max_length=150, blank=True, null=False, default="")
surname = models.CharField(max_length=150, blank=True, null=False, default="")
class Meta:
constraints = [
models.CheckConstraint(
name="%(app_label)s_%(class)s_firstname_and_or_surname",
check=(
Q(firstname__exact="", surname__exact!="")
| Q(firstname__exact!="", surname__exact="")
| Q(firstname__exact!="", surname__exact!="")
),
)
]
This should work except that, unlike surname_isnull=False, surname__exact!="" isn't valid syntax.
I know that if I had a queryset I could use exclude(surname__exact="") to mean "is not empty", but I'm not sure how to do that in this constraint with Q() expressions.
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您可以将
〜用作不是操作员：You can use
~as theNOToperator: