在Django模型中防止DateRangeField重叠？

Question

现在Django支持DateRangeField，是否有一个＆＃39; Pythonic＆＃39;防止记录重叠日期范围的方法？

假设用例

一个假设用例是预订系统，您不希望人们同时预订相同的资源。

假设示例代码

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',)

Answer 1

我知道答案很旧，但是现在您可以在模型的元数据中创建一个约束，这将使Postgres可以解决此问题

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),
            ),
        ]

Postgress Coonstraints

Answer 2

您可以在模型full_clean方法中进行检查，该方法在ModelForm验证期间会自动调用。如果您直接保存对象，则不会自动调用它。.这是Django验证的已知问题，您可能已经知道了！因此，如果要在保存对象的任何时间进行验证，则还必须重写模型save的方法。

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()