如何将上下文传递给Marshmallow中的嵌套序列化器？

Question

在他们的嵌套示例中：

class BlogSerializer(Serializer):
    title = fields.String()
    author = fields.Nested(UserSerializer)

# This is different! I'm passing in a context
serialized = BlogSerializer(blog, context={'test': 1})

UserSerializer在序列化博客时似乎没有获取到上下文信息。我该如何将上下文传递给嵌套的序列化器呢？

Answer 1

从 marshmallow 1.0.0-a 开始，嵌套字段的 Function 和 Method 字段会从它们的父级继承上下文。

from marshmallow import Schema, fields, pprint

class InnerSchema(Schema):
    value = fields.Function(lambda val, ctx: 'foo' in ctx['from_outer'])

class OuterSchema(Schema):
    inner = fields.Nested(InnerSchema)

schema = OuterSchema(context={'from_outer': 'foo'})
obj = {'inner': {}}
result = schema.dump(obj)
pprint(result.data)  # {"inner": {"value": true}}