fields.Method result should be able to be wrapped into other field types

fields.Method is pretty much always used to return a certain type of value. It doesn’t allow to choose options for the return value though.

For example, if one designes a field which should return a generic datetime and format it using a given format string, one is forced to use fields.Method which is linked to a schema method which returns a string(!), not a datetime. Because it is now impossible to provide a format string for the datetime anywhere except of the method itself.

In other words, something like this:

class MySchema(Schema):
    created_at = fields.Datetime(method='_created_at', format='%Y-%m-%dT%H:%M:%S%z')

    def _created_at(self, obj):
        return obj.metadata().creation_time()

would be much more convenient and reusable than this:

class MySchema(Schema):
    created_at = fields.Method('_formatted_created_at')

    def _formatted_created_at(self, obj):
        return obj.metadata().created_at().strftime('%Y-%m-%dT%H:%M:%S%z')

[lafrech]

from_field already exists. It is the attribute parameter.

We could add parameters dump_method and load_method. And deprecate Method field.

And likewise *_function, unless there is a way to do both functions and methods with the same parameter.

[1Mark]

Any progress on this?