我在我的视图中有一个列表理解，因为我必须根据模型计算字段进行过滤。
leaseterms = LeaseTerm.objects.filter( is_active = True )
tobe_payed_terms = [obj for obj in leaseterms if obj.current_balance < 0]
我用它来显示报告中的所有字段。
目前我必须添加一个仪表板，我只想显示此列表理解的总单位数。
最明智的表现方式是什么？
（我的仪表板中可能会出现这样的情况）
class LeaseTerm(CommonInfo):
version = IntegerVersionField( )
start_period = models.ForeignKey(Period, related_name='start_period',on_delete=models.PROTECT)
end_period = models.ForeignKey(Period, related_name='end_period',on_delete=models.PROTECT)
lease = models.ForeignKey(Lease,on_delete=models.PROTECT)
increase = models.DecimalField(max_digits=7, decimal_places=2)
amount = models.DecimalField(max_digits=7, decimal_places=2)
is_renewed = models.BooleanField(default=False)
is_renewal_letter = models.BooleanField(default=False)
renewal_letter_date = models.DateField(null=True, blank=True)
_current_period = None
_total_current = None
_total_payment = None
_total_current_payment = None
_total_discount = None
_total_current_discount = None
_current_tobe_payed = None
_current_balance = None
_is_current_term = None
_tenant = None
def _get_total(self):
from payment.models import LeasePayment
from conditions.models import LeaseDiscount
total_payment_dict = LeasePayment.objects.filter(leaseterm_id=self.id, is_active = True ).aggregate(Sum('amount'))
if total_payment_dict ['amount__sum']:
total_payment = total_payment_dict['amount__sum']
else:
total_payment = 0
total_discount_dict = LeaseDiscount.objects.filter(leaseterm_id=self.id, is_active = True ).aggregate(Sum('amount'))
if total_discount_dict ['amount__sum']:
total_discount = total_discount_dict['amount__sum']
else:
total_discount = 0
current_date=datetime.datetime.now().date()
current_period_dict = Period.objects.filter(start_date__lte=current_date,end_date__gte=current_date, is_active = True ).aggregate(Max('order_value'))
if current_period_dict['order_value__max']:
current_period = current_period_dict['order_value__max']
else:
current_period = 0
tenant = LeaseTenant.objects.filter(lease=self.lease, is_financially_accountable=True ).last()
if (self.start_period.order_value <= current_period <= self.end_period.order_value) and (self.is_active == True):
is_current_term_dict = True
else:
is_current_term_dict = False
current_period = self.end_period.order_value
current_discount_dict = LeaseDiscount.objects.filter(leaseterm_id=self.id,
is_active = True, period_date__gte=self.start_period,
period_date__lte=current_period).aggregate(Sum('amount'))
if current_discount_dict ['amount__sum']:
current_discount = current_discount_dict['amount__sum']
else:
current_discount = 0
current_periods_number = current_period - self.start_period.order_value + 1
current_tobe_payed = current_periods_number * self.amount - current_discount
current_balance = total_payment - current_tobe_payed
self._current_period = current_period
self._total_payment = total_payment
self._total_discount = total_discount
self._current_tobe_payed = current_tobe_payed
self._current_balance = current_balance
self._is_current_term = is_current_term_dict
if tenant is not None:
self._tenant = tenant.tenant
else:
self._tenant = None
@property
def is_current_term(self):
if self._is_current_term is None:
self._get_total()
return self._is_current_term
@property
def tenant(self):
if self._tenant is None:
self._get_total()
return self._tenant
@property
def current_tobe_payed(self):
if self._current_tobe_payed is None:
self._get_total()
return self._current_tobe_payed
@property
def current_balance(self):
if self._current_balance is None:
self._get_total()
return self._current_balance
@property
def current_period(self):
if self._current_period is None:
self._get_total()
return self._current_period
@property
def total_payment(self):
if self._total_payment is None:
self._get_total()
return self._total_payment
@property
def total_discount(self):
if self._total_discount is None:
self._get_total()
return self._total_discount
def save(self, *args, **kwargs):
self.full_clean()
return super(LeaseTerm, self).save(*args, **kwargs)
def __unicode__(self):
return u' %i %s %s ' % (self.id, self.start_period, self.end_period)
@with_author
class Period(CommonInfo):
version = IntegerVersionField( )
order_value = models.PositiveSmallIntegerField()
start_date = models.DateField()
end_date = models.DateField()
name = models.CharField(max_length=30)
duration = models.PositiveSmallIntegerField(null=True, blank=True)
is_special = models.BooleanField(default=False)
is_marked = models.BooleanField(default=False)
_is_current = models.NullBooleanField( blank=True, null=True, default=None)
#not_terminated_active_objects = NotTerminatedActiveManager()
def __unicode__(self):
return u'%s %i %s ' % ("#", self.order_value, self.name)
class Lease(CommonInfo):
version = IntegerVersionField( )
unit = models.ForeignKey(Unit,on_delete=models.PROTECT)
is_terminated = models.BooleanField(default=False)
_total = None
_total_current = None
_total_payment = None
_total_current_payment = None
_total_discount = None
_total_current_discount = None
def _get_total(self):
from payment.models import LeasePayment
from conditions.models import LeaseDiscount
total_payment_dict = LeasePayment.objects.filter(lease_id=self.id, is_active = True ).aggregate(Sum('amount'))
if total_payment_dict ['amount__sum']:
total_payment = total_payment_dict['amount__sum']
else:
total_payment = 0
total_discount_dict = LeaseDiscount.objects.filter(leaseterm__lease_id=self.id, is_active = True ).aggregate(Sum('amount'))
if total_discount_dict ['amount__sum']:
total_discount = total_discount_dict['amount__sum']
else:
total_discount = 0
self._total_payment = total_payment
self._total_discount = total_discount
self._total = total_payment + total_discount
@property
def total_payment(self):
if self._total_payment is None:
self._get_total()
return self._total_payment
@property
def total_discount(self):
if self._total_discount is None:
self._get_total()
return self._total_discount
@property
def total(self):
if self._total is None:
self._get_total()
return self._total
def __unicode__(self):
return u'%s %i %s ' % ("lease#", self.id, self.unit)
def clean(self):
model = self.__class__
if self.unit and (self.is_active == True) and model.objects.filter(unit=self.unit, is_terminated = False , is_active = True).exclude(id=self.id).count() > 0:
raise ValidationError('Unit has active lease already, Terminate existing one prior to creation of new one or create a not active lease '.format(self.unit))
def save(self, *args, **kwargs):
self.full_clean()
return super(Lease, self).save(*args, **kwargs)
class CommonInfo(models.Model):
created = models.DateTimeField("creation date", auto_now_add=True)
modified = models.DateTimeField("modification date", auto_now=True)
description = models.TextField(null=True, blank=True)
is_active = models.BooleanField(default=True)
class Meta:
abstract = True
答案 0 :(得分：0)
到目前为止我的解决方案：
leaseterms = LeaseTerm.objects.filter（is_active = True） negative_balance_term = [obj.urrent_balance＆lt;对象中的obj.id用于obj。 0] count_negative_balance_term = LeaseTerm.objects.filter（id__in = negative_balance_term）.count（）