使用棉花糖按字母顺序对字段值进行排序

Question

当 API 返回每个字段的值时，我需要按字母顺序对其进行排序。似乎 marshmallow 的 pre_dump 方法是在序列化之前预处理数据的方法，但我一直无法弄清楚这一点。我已经多次阅读文档并用谷歌搜索但没有找到答案。

class UserSettingsSchema(UserSchema):
    class Meta:
        fields = (
            "id",
            "injuries",
            "channel_levels",
            "movement_levels",
            "equipments",
            "goals",
            "genres"
        )

    @pre_dump
    def pre_dump_hook(): # what do I pass in here?
        # alphabetize field values, eg, all the genres will be sorted

    equipments = fields.Nested(EquipmentSchema, many=True)
    goals = fields.Nested(GoalSchemaBrief, many=True)
    genres = fields.Nested(GenreSchemaBrief, many=True)

Answer 1

如the docs所述：

By default, receives a single object at a time, regardless of whether many=True is passed to the Schema.

这是一个例子：

from marshmallow import *

class MySchema(Schema):

    name = fields.String()

    @pre_dump
    def pre_dump_hook(self, instance):
        instance['name'] = 'Hello %s' % instance['name']

现在您可以：

schema = MySchema()
schema.dump({'name': 'Bill'})

>>> MarshalResult(data={'name': 'Hello Bill'}, errors={})

Answer 2

PoP 给出的答案没有解决我需要对值进行排序的事实。我是这样做的：

@post_load
def post_load_hook(self, item):
    item['genres'] = sorted(item['genres'])
    return item

使用棉花糖按字母顺序对字段值进行排序

Sort field values alphabetically using marshmallow

python

python-3.x

marshmallow