Meta not inherited

https://github.com/marshmallow-code/marshmallow/issues/162

This issue which was solved a while ago seems to have came back. Meta on a baseschema, particularly ordered, is not carrying through or being inherited onto the next schema.

from datetime import datetime

from marshmallow import Schema, fields, validate

class BaseSchema(Schema):
    created_at = fields.Integer(validate=validate.Range(min=0), missing=int(datetime.utcnow().timestamp()))
    updated_at = fields.Integer(validate=validate.Range(min=0), missing=None)

    class Meta:
        ordered = True


class AlbumSchema(BaseSchema):
    title = fields.Str()

album = dict(title="Hunky Dory")

result = AlbumSchema().load(album)
result = AlbumSchema().dump(result)

[lafrech]

ordered does have an effect because the order of the fields depends on the set class being used. See #1744, where I propose to use an ordered set by default to get ordered schemas for (almost ?) free.

So we do need ordered to be inherited. But I agree meta attribute should be inherited, though. In fact, I use the same pattern in my apps: define an ordered base schema class.

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As a sidenote, this is wrong:

    missing=int(datetime.utcnow().timestamp())

because you get the datetime at schema declaration time, not instantiation time. You must use a lambda instead.

[deckar01]

I am unable to reproduce this with python 3.9 on marshmallow 3.14.0. I added assert(AlbumSchema.Meta == BaseSchema.Meta) to that example and it passes.

I assume you are on python 3 based on the timestamp usage. What version of marshmallow are you using?