既然 Django 支持 DateRangeField,是否有一种“Pythonic”方法来防止记录具有重叠的日期范围?
一个假设的用例是预订系统,您不希望人们同时预订相同的资源。
class Booking(models.model):
# The resource to be reserved
resource = models.ForeignKey('Resource')
# When to reserve the resource
date_range = models.DateRangeField()
class Meta:
unique_together = ('resource', 'date_range',)
我知道答案已经很旧了,但现在你可以在模型的元中创建一个约束,这将使 Postgres 处理这个问题
from django.contrib.postgres.constraints import ExclusionConstraint
from django.contrib.postgres.fields import DateTimeRangeField, RangeOperators
from django.db import models
from django.db.models import Q
class Room(models.Model):
number = models.IntegerField()
class Reservation(models.Model):
room = models.ForeignKey('Room', on_delete=models.CASCADE)
timespan = DateTimeRangeField()
cancelled = models.BooleanField(default=False)
class Meta:
constraints = [
ExclusionConstraint(
name='exclude_overlapping_reservations',
expressions=[
('timespan', RangeOperators.OVERLAPS),
('room', RangeOperators.EQUAL),
],
condition=Q(cancelled=False),
),
]
为了使其工作,您还需要激活 PostgreSQL 上的
btree_gist
扩展。
您可以通过在迁移文件中添加以下行来完成此操作
from django.contrib.postgres.operations import BtreeGistExtension
class Migration(migrations.Migration):
operations = [
BtreeGistExtension(),
...
]
您可以在模型
full_clean
方法中检查这一点,该方法在 ModelForm 验证期间自动调用。 如果你直接保存对象,它不会被自动调用。这是 Django 验证的一个已知问题,你可能已经意识到了! 因此,如果您希望在保存对象时随时进行验证,则还必须重写模型 save
方法。
class Booking(models.model):
def full_clean(self, *args, **kwargs):
super(Booking, self).full_clean(*args, **kwargs)
o = Booking.objects.filter(date_range__overlap=self.date_range).exclude(pk=self.pk).first()
if o:
raise forms.ValidationError('Date Range overlaps with "%s"' % o)
# do not need to do this if you are only saving the object via a ModelForm, since the ModelForm calls FullClean.
def save(self):
self.full_clean()
super(Booking, self).save()