举例讲解Django中数据模型访问外键值的方法

from django.db import models

class Publisher(models.Model):
 name = models.CharField(max_length=30)
 address = models.CharField(max_length=50)
 city = models.CharField(max_length=60)
 state_province = models.CharField(max_length=30)
 country = models.CharField(max_length=50)
 website = models.URLField()

 def __unicode__(self):
 return self.name

class Author(models.Model):
 first_name = models.CharField(max_length=30)
 last_name = models.CharField(max_length=40)
 email = models.EmailField()

 def __unicode__(self):
 return u'%s %s' % (self.first_name, self.last_name)

class Book(models.Model):
 title = models.CharField(max_length=100)
 authors = models.ManyToManyField(Author)
 publisher = models.ForeignKey(Publisher)
 publication_date = models.DateField()

 def __unicode__(self):
 return self.title

>>> b = Book.objects.get(id=50)
>>> b.publisher

>>> b.publisher.website
u'http://www.apress.com/'

>>> p = Publisher.objects.get(name='Apress Publishing')
>>> p.book_set.all()
[, , ...]

>>> p = Publisher.objects.get(name='Apress Publishing')
>>> p.book_set.filter(name__icontains='django')
[, ]