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除了文档中的一个示例之外，我找不到任何关于 django 如何准确选择可以从父对象访问子对象的名称的文档。在他们的示例中，他们执行以下操作：

    class Place(models.Model):
        name = models.CharField(max_length=50)
        address = models.CharField(max_length=80)

        def __unicode__(self):
            return u"%s the place" % self.name

    class Restaurant(models.Model):
        place = models.OneToOneField(Place, primary_key=True)
        serves_hot_dogs = models.BooleanField()
        serves_pizza = models.BooleanField()

        def __unicode__(self):
            return u"%s the restaurant" % self.place.name

    # Create a couple of Places.
    >>> p1 = Place(name='Demon Dogs', address='944 W. Fullerton')
    >>> p1.save()
    >>> p2 = Place(name='Ace Hardware', address='1013 N. Ashland')
    >>> p2.save()

    # Create a Restaurant. Pass the ID of the "parent" object as this object's ID.
    >>> r = Restaurant(place=p1, serves_hot_dogs=True, serves_pizza=False)
    >>> r.save()

    # A Restaurant can access its place.
    >>> r.place
    <Place: Demon Dogs the place>
    # A Place can access its restaurant, if available.
    >>> p1.restaurant

因此，在他们的示例中，他们只是调用 p1.restaurant 而不明确定义该名称。Django 假定名称以小写字母开头。如果对象名称包含多个单词，例如 FancyRestaurant，会发生什么情况？

旁注：我正在尝试以这种方式扩展 User 对象。这可能是问题吗？

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1 回答 1

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如果您定义一个自定义related_name，那么它将使用它，否则它将小写整个模型名称（在您的示例中.fancyrestaurant）。查看django.db.models.related 代码中的 else 块：

def get_accessor_name(self):
    # This method encapsulates the logic that decides what name to give an
    # accessor descriptor that retrieves related many-to-one or
    # many-to-many objects. It uses the lower-cased object_name + "_set",
    # but this can be overridden with the "related_name" option.
    if self.field.rel.multiple:
        # If this is a symmetrical m2m relation on self, there is no reverse accessor.
        if getattr(self.field.rel, 'symmetrical', False) and self.model == self.parent_model:
            return None
        return self.field.rel.related_name or (self.opts.object_name.lower() + '_set')
    else:
        return self.field.rel.related_name or (self.opts.object_name.lower())

这就是它的OneToOneField调用方式：

class OneToOneField(ForeignKey):
    ... snip ...

    def contribute_to_related_class(self, cls, related):
        setattr(cls, related.get_accessor_name(),
                SingleRelatedObjectDescriptor(related))

opts.object_name（在 django.db.models.related.get_accessor_name 中引用）默认为cls.__name__.

至于

旁注：我正在尝试以这种方式扩展 User 对象。这可能是问题吗？

不，它不会，该User模型只是一个普通的 django 模型。只要注意related_name碰撞。

于 2010-09-13T23:32:20.450 回答