Django-REST框架restore_object attrs参数

Question

找到Django-REST框架文档,尽管它有多长,但对我来说仍然太过背景.

restore_object方法的attrs函数有什么作用？

instance.title = attrs.get('title', instance.title)

第二个论点代表什么,以及我将如何在未来的文档中寻找这将意味着什么？

也不确定双星号是什么return Snippet(**attrs)意思.这与**keywArgs不同？将哪些参数传递回反序列化的Snippet对象？

在文档的另一部分中,我在restore_object()中看到instance.title = attrs['title'],我希望有人能够看到我的困惑.

谢谢

class SnippetSerializer(serializers.Serializer):
    pk = serializers.Field()  # Note: `Field` is an untyped read-only field.
    title = serializers.CharField(required=False,
                                  max_length=100)
    code = serializers.CharField(widget=widgets.Textarea,
                                 max_length=100000)
    linenos = serializers.BooleanField(required=False)
    language = serializers.ChoiceField(choices=LANGUAGE_CHOICES,
                                       default='python')
    style = serializers.ChoiceField(choices=STYLE_CHOICES,
                                    default='friendly')

    def restore_object(self, attrs, instance=None):
        """
        Create or update a new snippet instance.
        """
        if instance:
            # Update existing instance
            instance.title = attrs.get('title', instance.title)
            instance.code = attrs.get('code', instance.code)
            instance.linenos = attrs.get('linenos', instance.linenos)
            instance.language = attrs.get('language', instance.language)
            instance.style = attrs.get('style', instance.style)
            return instance

        # Create new instance
        return Snippet(**attrs)

Answer 1

我稍微更新了文档,旨在使其更加清晰......

http://django-rest-framework.org/tutorial/1-serialization.html#creating-a-serializer-class

该方法现在读取...

def restore_object(self, attrs, instance=None):
    """
    Create or update a new snippet instance, given a dictionary
    of deserialized field values.

    Note that if we don't define this method, then deserializing
    data will simply return a dictionary of items.
    """
    if instance:
        # Update existing instance
        instance.title = attrs.get('title', instance.title)
        instance.code = attrs.get('code', instance.code)
        instance.linenos = attrs.get('linenos', instance.linenos)
        instance.language = attrs.get('language', instance.language)
        instance.style = attrs.get('style', instance.style)
        return instance

    # Create new instance
    return Snippet(**attrs)

该**attrs风格使用Python的标准关键字扩展.在这里看到一个很好的解释.

它最终会相当于 Snippet(title=attrs['title'], code=attrs['code'], ...)

希望有所帮助!