base.py 文件源码

def _prepare(cls):
        """
        Creates some methods once self._meta has been populated.
        """
        opts = cls._meta
        opts._prepare(cls)

        if opts.order_with_respect_to:
            cls.get_next_in_order = curry(cls._get_next_or_previous_in_order, is_next=True)
            cls.get_previous_in_order = curry(cls._get_next_or_previous_in_order, is_next=False)

            # defer creating accessors on the foreign class until we are
            # certain it has been created
            def make_foreign_order_accessors(field, model, cls):
                setattr(
                    field.rel.to,
                    'get_%s_order' % cls.__name__.lower(),
                    curry(method_get_order, cls)
                )
                setattr(
                    field.rel.to,
                    'set_%s_order' % cls.__name__.lower(),
                    curry(method_set_order, cls)
                )
            add_lazy_relation(
                cls,
                opts.order_with_respect_to,
                opts.order_with_respect_to.rel.to,
                make_foreign_order_accessors
            )

        # Give the class a docstring -- its definition.
        if cls.__doc__ is None:
            cls.__doc__ = "%s(%s)" % (cls.__name__, ", ".join(f.name for f in opts.fields))

        get_absolute_url_override = settings.ABSOLUTE_URL_OVERRIDES.get(
            '%s.%s' % (opts.app_label, opts.model_name)
        )
        if get_absolute_url_override:
            setattr(cls, 'get_absolute_url', get_absolute_url_override)

        ensure_default_manager(cls)
        signals.class_prepared.send(sender=cls)