多个For循环Django

Question

我有以下两种型号ASPBoookings和Athlete。运动员模型由外国关键指定运动员链接到ASPBookings模型。

我正在尝试创建一个循环，循环浏览ASPBooking表中的所有预订，并找出每个运动员的最新预订(该表可以包含同一或不同运动员的多个预订(athlete_id((。

一旦我有了这个信息(booking_date和athlete_id(，我就希望能够自动更新"；最后ASP会话字段"；在运动员模型中。

这就是我迄今为止所尝试的。我可以循环浏览ASPBookings表中的预订；"最新ASP会话字段"；使用booking_date和athlets_id，但我不能为表中的多个不同运动员执行此操作。目前，该视图只识别最近的预订和分配的athlete_id，然后更新字段。

提前感谢您的帮助。

以下是代码：

ASP预订模型

class ASPBookings(models.Model):
asp_booking_ref = models.CharField(max_length=10, default=1)
program_type = models.CharField(max_length=120, default='asp')
booking_date = models.DateField()
booking_time = models.CharField(max_length=10, choices=booking_times)
duration = models.CharField(max_length=10, choices=durations, default='0.5')
street = models.CharField(max_length=120)
suburb = models.CharField(max_length=120)
region = models.CharField(max_length=120, choices=regions, default='Metro')
post_code = models.CharField(max_length=40)
organisation_type = models.CharField(max_length=120,choices=organisation_types, default='Government School')
audience_number = models.CharField(max_length=10)
presentation_form = models.CharField(max_length=120, choices=presentation_form_options, default='Face to Face')
contact_name = models.CharField(max_length=80)
email = models.EmailField()
phone_number = models.CharField(max_length=120)
comments = models.TextField()
status = models.CharField(max_length=80, choices=statuses, default='TBC')
email_sent = models.BooleanField(default=False)
athlete = models.ForeignKey(Athlete, default= '1', on_delete=models.CASCADE)
def __str__(self):
return self.contact_name

# return URL after the POST has been submitted.
def get_absolute_url(self):
return reverse('vistours:success')

运动员模型

class Athlete(models.Model):
athlete_ref = models.CharField(max_length=10, default=1)
athlete_name = models.CharField(max_length=80)
email = models.EmailField()
phone_number = models.CharField(max_length=120)
home = models.CharField(max_length=120)
education = models.CharField(max_length=120)
sport = models.CharField(max_length=120, choices=sports, default='1500m Runner')
notes = models.TextField(default='None')
gender = models.CharField(max_length=120, choices=genders, default='Not Specified')
para_athlete = models.BooleanField(blank=True)
working_with_children = models.BooleanField(blank=True)
expiry_date = models.DateField(blank=True, null=True)
available = models.BooleanField(blank=True)
available_from = models.DateField(blank=True, null=True)
bfbw = models.BooleanField(blank=True)
latest_bfbw_session = models.DateField(blank=True, null=True)
number_bfbw_sessions = models.CharField(blank=True, null=True, max_length=10)
asp = models.BooleanField(blank=True)
latest_asp_session = models.DateField(blank=True, null=True)
number_asp_sessions = models.CharField(blank=True, null=True, max_length=10)
tours = models.BooleanField(blank=True)
latest_tours_session = models.DateField(blank=True, null=True)
number_tours_sessions = models.CharField(blank=True, null=True, max_length=10)
def __str__(self):
return self.athlete_name
# return URL after the POST has been submitted.
def get_absolute_url(self):
return reverse('home')

查看

# Complete first loop for inital values.
for date in asp_data:
if date.booking_date != None:
first_loop = date.booking_date
athl_id = date.athlete_id
break
# If next value is greater than inital value, replace current values.      
for date in asp_data:
if date.booking_date != None:
if date.booking_date > first_loop:
first_loop = date.booking_date
athl_id = date.athlete_id

print(first_loop)
print(athl_id)
update_date = Athlete.objects.get(id=athl_id)
update_date.latest_asp_session = first_loop
update_date.save()

Answer 1

不需要循环。您可以使用子查询为所有运动员一次性完成这项工作，将所有繁重的工作留给您的数据库：

from django.db.models import F, OuterRef, Subquery
bookings = ASPBookings.objects.filter(
athlete=OuterRef('pk')
).order_by('-booking_date')
Athlete.objects.annotate(
latest_asp_booking_date=Subquery(
bookings.values('booking_date')[:1]
)
).update(
latest_asp_session=F('latest_asp_booking_date')
)