ChangedInMarshmallow3Warning with Python 3.7

Using Python 3.7 and having installed it the standard way™:

$ pip install marshmallow

I get an unexpected warning:

/usr/local/lib/python3.7/dist-packages/marshmallow/schema.py:364: ChangedInMarshmallow3Warning: strict=False is not recommended. In marshmallow 3.0, schemas will always be strict. See https://marshmallow.readthedocs.io/en/latest/upgrading.html#schemas-are-always-strict ChangedInMarshmallow3Warning

And despite what the documentation says, <form>.load(…) returns a tuple but shouldn’t.

minimal example (not authoritative)

import typing import Tuple
from marshmallow import fields, Schema, ValidationError

class RegistrationSchema(Schema):
    email = fields.Email(required=True)

try:
    result = RegistrationSchema().load({'email', 'nospam'})
    if isinstance(result, Tuple):
        print('unexpected')
except ValidationError as err:
    print('ok')

# → gives: "unexpected"

[sloria]

@rtaft You’re right. I was able to reproduce it. I’ve opened a new bug issue: #1134.

[lafrech]

pip install marshmallow

installs marshmallow 2, as marshmallow 3 is still beta.

This warning was added to marshmallow 2 to prepare marshmallow 3 migration. You may ignore it, or make all your schemas strict to be ready for the migration. (Hint: you may declare a strict base schema and have all your schemas inherit from it.)

The tuple is expected return value for marshmallow 2. I suppose you read marshmallow 3 documentation.