Django-教程模型第5章

Question

我目前正在通过Django-book教程学习Django，我遇到了一个错误。在第5章，我应该在python解释器中输入这段代码。

    >>> p1 = Publisher.objects.create(name='Apress', 
    ... address='2855 Telegraph Avenue', 
    ... city='Berkeley', state_province='CA', country='U.S.A.', 
    ... website='http://www.apress.com/') 
    >>> p2 = Publisher.objects.create(name="O'Reilly", 
    ... address='10 Fawcett St.', city='Cambridge', 
    ... state_province='MA', country='U.S.A.', 
    ... website='http://www.oreilly.com/') 
    >>> publisher_list = Publisher.objects.all() 
    >>> publisher_list 

根据本教程，我应该得到以下输出

    [<Publisher: Publisher object>, <Publisher: Publisher object>] 

然而，我得到了相同的输出，但是有4个对象！

    [<Publisher: Publisher object>, <Publisher: Publisher object>, <Publisher: Publisher object>, <Publisher: Publisher object>] 

另外，我应该将我的models.py从django.db导入模型更改为这个(添加了unicode函数)

    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 

以便显示对象。以下是根据本教程的输出

    >>> from books.models import Publisher 
    >>> publisher_list = Publisher.objects.all() 
    >>> publisher_list 
    [<Publisher: Apress>, <Publisher: O'Reilly>] 

但我还是得到了

    [<Publisher: Publisher object>, <Publisher: Publisher object>, <Publisher: Publisher object>, <Publisher: Publisher object>] 

不确定为什么我得到了更多的对象，为什么我不能查看unicode的输出...

谢谢你的帮助!

**http://django-book.readthedocs.org/en/latest/chapter05.html是指向特定章节的链接！

Answer 1

尝试此示例：

models.py

class Debt(models.Model):
    user = models.ForeignKey(User)
    name = models.CharField(max_length=50,
        help_text="Name to identify your debt.")
    due_day = models.PositiveSmallIntegerField(
        help_text="Day of the month payment is due.")

    def __unicode__(self):
        return "{0}".format(self.user)

views.py

def debt(request):

return render(request, 'debt.html', {
    'debts': Debt.objects.filter(),
}) 

debt.html

 {% for debt in debts %}
     {{debt.user}} - {{debt.name}} <br/>
 {% endfor %}  

Answer 2

这是因为您已经运行了两次代码。这些值已保存在数据库中。当您再次运行它时，又保存了两个值，它们是重复的。