attribute used instead of data_key during deserialization

This may be related to #748. When a data_key is provided for a field the deserialized data contains the wrong key.

import marshmallow as mm


class TestSchema(mm.Schema):
    type = mm.fields.String(attribute='_type', data_key='type')


data = {
    'type': 'value'
}

assert TestSchema().load(data) == data

[lafrech]

Use one schema for loading and one for dumping.

class FooLoad(Schema):
    name = fields.Str()
    email = fields.Email(data_key='emailAddress')

class FooDump(Schema):
    name = fields.Str()
    email = fields.Email()

schema_dump = FooDump()
schema_dump.dump({'name': 'foo', 'email': '[e-mail]'})
# {'name': 'foo', 'email': '[e-mail]'}

schema_load = FooLoad()
schema_load.load({'name': 'foo', 'emailAddress': '[e-mail]'})
# {'name': 'foo', 'email': '[e-mail]'}

[djlambert]

I’ll just delete the _type key so I don’t have to update all my models. Thanks for your help! This issue can be closed.