本文介绍了Django orm按天数整数筛选日期时间的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
我有一个名为AccessDuration的模型，它有两个重要的字段：duration(Int)和lab_start_date(DateTime)。基于这两个字段，我想检查访问持续时间是否已过期。这是通过使用模型函数完成的。
class AccessDuration(models.Model):
....
duration = models.PositiveIntegerField(default=30, help_text=_('In days'))
lab_start_date = models.DateTimeField(verbose_name=('Start Date'), null=True)
@property
def expiration_date(self) -> Union[timezone.datetime, None]:
if self.lab_start_date:
return self.lab_start_date + timezone.timedelta(days=self.duration)
return None
@property
def is_expired(self) -> bool:
""" to check whether duration already expired or yet """
if self.expiration_date:
return timezone.now() > self.expiration_date
return False
from django.db import models
from django.contrib import admin
from django.utils.translation import ugettext_lazy as _
from django.utils import timezone
from .models import AccessDuration
class AccessListFilter(admin.SimpleListFilter):
title = _('Is Expired')
parameter_name = 'is_expired'
def lookups(self, request, model_admin):
return [
('true', _('True')),
('false', _('False'))
]
def queryset(self, request, queryset):
value = self.value()
expiration_date = models.ExpressionWrapper(
models.F('lab_start_date') + (timezone.timedelta(days=1) * models.F('duration')),
output_field=models.DateTimeField()
)
if value == 'true':
return queryset.annotate(expiration_date=expiration_date)
.filter(expiration_date__lt=timezone.now())
elif value == 'false':
return queryset.annotate(expiration_date=expiration_date)
.filter(expiration_date__gte=timezone.now())
return queryset
class AccessAdmin(admin.ModelAdmin):
list_filter = (AccessListFilter, 'lab_start_date')
admin.site.register(AccessDuration, AccessAdmin)
我发现的错误；
@William解决后，我对Manager做了一些修改；
class AccessDurationQuerySet(models.QuerySet):
def filter_expiration(self, is_expired: bool = False):
"""
To filter whether AccessDuration already expired or yet.
don't use the same `expiration_date` as expression key,
because it will clash with `AccessDuration.expiration_date` property.
Issue: https://stackoverflow.com/q/69012110/6396981
"""
kwargs = {'_expiration_date__gte': Now()}
if is_expired:
del kwargs['_expiration_date__gte']
kwargs['_expiration_date__lt'] = Now()
return self.all().annotate(
_expiration_date=models.ExpressionWrapper(
models.F('lab_start_date') + (timezone.timedelta(days=1) * models.F('duration')),
output_field=models.DateTimeField()
)
).filter(**kwargs)
class AccessDurationManager(
models.Manager.from_queryset(AccessDurationQuerySet),
DefaultManager
):
def published(self):
return super().published().filter(
status=AccessDurationStatusChoices.active
)
class AccessDuration(models.Model):
....
objects = AccessDurationManager()
然后在我们的ORM中；
AccessDuration.objects.filter_expiration(is_expired=True)
或在我们的admin.py；
class ExpirationListFilter(admin.SimpleListFilter):
title = _('Is Expired')
parameter_name = 'is_expired'
def lookups(self, request, model_admin):
return [
(True, True),
(False, False)
]
def queryset(self, request, queryset):
value = str(self.value()).lower()
if value == 'true':
return queryset.filter_expiration(is_expired=True)
elif value == 'false':
return queryset.filter_expiration(is_expired=False)
return queryset
class AccessAdmin(admin.ModelAdmin):
...
list_filter = (ExpirationListFilter, ...)
推荐答案
您应该使用expiration_date要批注的其他名称。例如：
from django.db.models.functions import Now
if value == 'true':
return queryset.annotate(
_expiration_date=expiration_date
).filter(_expiration_date__lt=Now())
elif value == 'false':
return queryset.annotate(
_expiration_date=expiration_date
).filter(_expiration_date__gte=Now())这篇关于Django orm按天数整数筛选日期时间的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持编程学习网！
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