List(Nested()) 在嵌套架构中不使用 `many`

from marshmallow import Schema, fields, post_dump


class ItemSchema(Schema):
    id = fields.Integer()
    name = fields.String()

    @post_dump(pass_many=True)
    def query_extra_data(self, data, many, **kwargs):
        print(f'post_dump called: {many=} {data=}')


class TestSchema(Schema):
    items = fields.List(fields.Nested(ItemSchema))


data = {'items': [
    {'id': 1, 'name': 'foo'},
    {'id': 2, 'name': 'bar'},
    {'id': 3, 'name': 'snafu'},
]}

TestSchema().dump(data)

post_dump called: many=False data={'name': 'foo', 'id': 1}
post_dump called: many=False data={'name': 'bar', 'id': 2}
post_dump called: many=False data={'name': 'snafu', 'id': 3}

post_dump called: many=True data=[{'name': 'foo', 'id': 1}, {'name': 'bar', 'id': 2}, {'name': 'snafu', 'id': 3}]