我对django比较新，并且在将一些信息从一个模型传递到另一个模型时遇到问题。它不是完全继承，而是确保父模型在创建子模型时传递某些信息。所以我有两个模型，一个用于事件，另一个用于事件。事件通过管理员运行，当您创建事件时，它还会为该事件创建事件。我的问题是每个事件都在一个特定的城市，我希望它将城市值传递给它创建的事件，以便我可以在过滤器中使用该城市值。应该注意，事件不是事件，因此这不仅仅是多表继承。我如何传递这个值？
Models.py
# The events are models that contain the what and where.
class Event(models.Model):
class Meta:
verbose_name_plural = 'Events'
verbose_name = 'Event'
created = models.DateTimeField(auto_now=False, auto_now_add=True, blank = False, null = False, verbose_name = 'Creation Date')
#Date Event was edited for the last time
updated = models.DateTimeField(auto_now=True, auto_now_add=False, blank = False, null = False, verbose_name = 'Updated')
#Name of the event
name = models.CharField(max_length = 400, null=True, blank = False, verbose_name = 'Name')
#Event Description
description = models.TextField(max_length = 10000, null=True, blank = True, verbose_name = 'Description')
#Event City
city = models.ForeignKey(City, null=True, blank = False, verbose_name = 'City')
#Event Location
location = ChainedForeignKey(
ProfileVenue,
chained_field="city",
chained_model_field="city",
show_all=False,
auto_choose=True,
sort=True,
default=1,)
#Price Entity
price = models.ForeignKey(Price, null=True, blank = True,)
#Max Number of participants
max_participants = models.IntegerField(null=True, blank = False, verbose_name = 'Nr. Participants')
#Event Language
language = models.ForeignKey(Language, null = True, blank = False)
#Event Type
event_type = models.ForeignKey(EventType, null = True, blank =False, verbose_name='Event Type')
#---------------------------------------------------------------------------
def __unicode__(self):
return "%s:%s" % (self.name, self.location.name)
class Occurrence(models.Model):
class Meta:
verbose_name_plural = 'Sessions'
verbose_name = 'Session'
created = models.DateTimeField(auto_now=False,
auto_now_add=True, blank = False, null = False, verbose_name = 'Creation Date')
updated = models.DateTimeField(auto_now=True,
auto_now_add=False, blank = False, null = False, verbose_name = 'Updated')
event = models.ForeignKey(Event,
on_delete=models.CASCADE)
'''
city = ChainedForeignKey(
Event,
chained_field="city",
chained_model_field="city",
show_all=False,
auto_choose=True,
sort=True)
'''
teacher = models.ForeignKey(ProfileTeacher,
null=True, blank = True, verbose_name = 'Teacher')
students = models.ManyToManyField(ProfileStudent,
verbose_name = 'Students', blank=True)
# Max number of students for this group
max_participants = models.IntegerField(null=False,
blank=False, default=5, verbose_name='Max Nr Participants')
# Date and Time for this session
date = models.DateTimeField(auto_now=False,
auto_now_add=False, null=True, blank=True, verbose_name='Date')
# Duration of the class
duration = models.DurationField(default=timedelta(), verbose_name='Duration')
# Language Levels
language_level = models.ForeignKey(LanguageLevel,
null=True, blank=True, verbose_name='Language Level')
# True of teacher was assigned to class
teacher_assigned = models.BooleanField(
default=False, blank=True)
# Status of the Occurrence
# Active --> Class has been created
# Canceled --> Canceled by human admin
# Auto Canceled --> Canceled by the Automation System
# Due --> Class finished. Student Evaluated. Teacher Can get Extraction.
STATUS = (
(1, ('ACTIVE')),
(2, ('CANCELED')),
(3, ('DUE')),
(4, ('AUTO CANCELED')),
)
status = models.IntegerField(choices=STATUS, default=1)
# Evaluated by teacher: True if a teacher evaluated all students
students_ev_by_teacher = models.BooleanField(default=False, verbose_name='Alumnos evaluados')
# If true Send Mails when occurrence canceled to all teachers that are not assigned and students
send_cancel_mail = models.BooleanField(default=True, verbose_name='Enviar Email Cancelar')
# friendlly url
slug = models.SlugField(max_length=300, verbose_name='Occurrence Url', blank=True, null=True)
class EventForm(forms.ModelForm):
list_filter = ['city']
#Frequecy type for periodical events
FREQUENCY = (
('NEVER', ('Nunca')),
# ('DAILY', _('Every Day')),
('WEEKDAY', ('Cada Semana')),
# ('WEEKLY', _('Every Week')),
# ('BIWEEKLY', _('Every 2 Weeks')),
# ('MONTHLY', _('Every Month')),
)
# Weekday choices
WEEKDAYS = (
( 0, ('Lunes')),
( 1, ('Martes')),
( 2, ('Miercoles')),
( 3, ('Jueves')),
( 4, ('Viernes')),
( 5, ('Sabado')),
( 6, ('Domingo')),
)
#Date of the first Occurrence
start_date = forms.SplitDateTimeField(
widget = widgets.AdminSplitDateTime(),
help_text='Date and hour of the Event.',
required= True,
)
#Limit Date for last Occurrence: no hour needed
end_date = forms.SplitDateTimeField(
widget = widgets.AdminSplitDateTime(),
required = False,
help_text='Date and hour of the Event.',
)
#Event frequency tipe: weekly and never supported only
freq = forms.ChoiceField(
choices=FREQUENCY,
initial='WEEKDAY',
label = 'Tipo Periodicidad'
)
#The event wwill occure on this weekday once a week until the end date
weekday = forms.ChoiceField(
choices=WEEKDAYS,
widget=forms.RadioSelect(),
initial=1
)
#Event Duration in hours: stored as timedelta in database
duration = forms.DurationField(
initial='01:00:00',
)
#Class Meta
class Meta:
model = Event
fields = ('name',
'event_type',
'description',
'city',
'location',
'language',
'price',
'max_participants',
'start_date',
'end_date',
'freq',
'weekday',
'duration',
)
#End Date Validation:
def clean_end_date(self):
if self.cleaned_data['end_date'] > self.cleaned_data['start_date']:
return self.cleaned_data['end_date']
else:
raise ValidationError('End-Date should be higher than Start-Date!', code='invalid')
#End Date Validation: Occurences shall not be created when an event is updated
#This will create too many objects and confusion.
#Save the Validated Form
def save(self, commit=True):
#Getting the cleaned data
freq = self.cleaned_data.get('freq', None)
start_date = self.cleaned_data.get('start_date', None)
end_date = self.cleaned_data.get('end_date', None)
weekday = int(self.cleaned_data.get('weekday', None))
duration = self.cleaned_data.get('duration', None)
#Saving the Event
self.instance.save()
#Loading Language Levels
levels = LanguageLevel.objects.all()
#Calculate Max Participants for Occurrences
#This shall be a function of the type of the event
max_participants = 5;
#Create Occurrences from dates(see dateutil.rrule doc's for details):
if freq == 'NEVER':
for level in levels:
#Check for Future Occurrences:
oc = Occurrence(
date=start_date,
event=self.instance,
duration=duration,
max_participants=max_participants,
language_level=level,
)
oc.save()
#One per week until End_Date
elif freq == 'WEEKDAY':
oc_dates = rrule(WEEKLY, dtstart = start_date, byweekday = weekday, until=end_date)
for oc_date in oc_dates:
for level in levels:
oc = Occurrence(
date=oc_date,
event=self.instance,
duration=duration,
max_participants=max_participants,
language_level=level,
)
oc.save()
#Saving the Event
return super(EventForm, self).save(commit=commit)
答案 0 :(得分：0)
您有一个事件的外键，您可以使用该外键访问该城市，例如使用属性：
class Occurrence(models.Model):
[...]
@property
def city(self):
return self.event.city
无需在数据库中复制数据。
答案 1 :(得分：0)
感谢@DanielRoseman提供了这个答案。我的问题是我没有使用双下划线语法，这使我能够访问我的＆＃34;事件＆＃34;属性。即.filter(event__city=cityId)。其完整文件here