python - Marshmallow:嵌套模式字典

Question

我想知道如何序列化嵌套Schema的字典。

天真地，我希望这样的语法能够工作:

fields.List(Schema)
fields.Dict(Schema)

或者也许

fields.List(fields.Nested(Schema))
fields.Dict(fields.Nested(Schema))

序列化Schema列表可以通过Nested(Schema, Many=True)来实现，但我不知道dict > 架构。

假设，例如，我的对象定义如下:

from marshmallow import Schema, fields, pprint

class AlbumSchema(Schema):
    year = fields.Int()

class ArtistSchema(Schema):
    name = fields.Str()

    # What should I write, here?

    # This won't work
    albums = fields.Nested(AlbumSchema(), many=True)

    # If I write this, AlbumSchema is ignored, so this is equivalent to
    albums = fields.Dict(AlbumSchema(), many=True)
    # this, which is not satisfying (AlbumSchema unused)
    albums = fields.Dict()
    # This is not the way either
    albums = fields.Dict(fields.Nested(AlbumSchema))


album_1 = dict(year=1971)
album_2 = dict(year=1970)
bowie = dict(name='David Bowie',
             albums={
                 'Hunky Dory': album_1,
                 'The Man Who Sold the World': album_2
             }
        )

schema = ArtistSchema()
result = schema.dump(bowie)
pprint(result.data, indent=2)

我希望我的对象被序列化为

{ 'albums': { 'Hunky Dory': {'year': 1971},
              'The Man Who Sold the World': {'year': 1970}},
  'name': 'David Bowie'}

(问题还讨论了 on GitHub 。)

Answer 1

目前不可能，但这是一个功能请求:

• https://github.com/marshmallow-code/marshmallow/issues/483
• https://github.com/marshmallow-code/marshmallow/issues/496

并且已经开始工作:

• https://github.com/marshmallow-code/marshmallow/compare/dev...deckar01:483-structured-dict

2017-12-31:此功能已添加到 Marshmallow 3.0.0b5 ( https://github.com/marshmallow-code/marshmallow/pull/700 )。