Django通过集合查询

Question

I'm new to Django and I'm stuck at querying through multiple sets.

I have three models;

class Project(models.Model):
    name = models.CharField(max_length = 100)

class AppointmentGroup(models.Model):
    name = models.CharField(max_length = 100) # not used in design.. delete when not used at the end of the project
    project = models.ForeignKey(Project)
    location = models.ForeignKey(Location)

class Appointment(models.Model):
    appointment_group = models.ForeignKey(AppointmentGroup)
    start_date = models.DateTimeField()
    end_date = models.DateTimeField()

Now I want a returned object set with only the projects that have appointments within a particular year. And that the appointment set objects in the project object contains only the ones in that year!

Is this easy to do with a django query or must i loop through the projects one by one and check all the appointments on the date?

Answer 1

I'm guessing that the appointment model is some how related to your projects and you just left that off.

You probably want to use range and lookups that span relationships :

import datetime
start = datetime.date(2010, 1, 1)
end = datetime.date(2010, 12, 31)
projects_in_2010 = Projects.objects.filter(appointmentgroup__appointment__start_date__range(start, end))

Answer 2

尝试这个

AppointmentGroup.objects.filter(appoinment_set__start_date__year=2011, appoinment_set__end_date__year=2011)