Support Enum for Select-field

I have got some use cases where I use a Enum in my models.

Example:

# definitions.py
from enum import Enum

class Gender(Enum):
    male = 'm'
    female = 'f'

# models.py
from definitions import Gender

class Person:
    def __init__(self, gender: Gender):
        self.gender = gender

Now it would be great if I could use the Enum in marshmallow.fields.Select:

# schemas.py
from marshmallow import fields, Schema
from definitions import Gender
from models import Person

class PersonSchema(Schema):
    gender = fields.Select(Gender)

    @staticmethod
    def make_object(data) -> Person:
        return Person(**data)

For backwards-compatibility enum34 could be used.

[deckar01]

The Enum class is part of the standard library in python 3. If the intention is to map a string to an Enum instance, it would make sense for this to be a field rather than just a validator. We could probably support the Enum interface without needing to import enum to preserve compatibility with python 2. A new field doesn’t have to be part of a major release. It could be added in any minor version.

https://docs.python.org/3/library/enum.html

[justanr]

@deckar01 Supporting the read from and to interface of Enum can be supported without importing the module.

If this is of interest to have in marshmallow itself, I’m happy to contribute the code over. We can reconvene this when y’all are comfortable taking it on and figure out a migration path for it.