PynamoDB version 4 Breaking changes

[DavidM42]

I updated the packages of my project and had problems with the use of this plugin.
I think it's related to the Breaking changes in the major relase 4.0 of pynamodb I installed.
To be honest I am not 100% sure it was this project but I think the changes to pynamodb could cause problems here

[DavidM42]

I'm now pretty sure that new versions of pynamodb and/or marshmallow break this library
I currently have these versions locked in for my use as some newer combinations don't work:

flask==1.1.0
marshmallow==2.20.3
marshmallow-pynamodb
botocore==1.12.130
pynamodb==3.3.3
flask-smorest==0.18.2

Maybe I'll try to fix the problems caused by pynamodb version 4 changes but any help updating this library would be great

[kycunnin]

Hey David,
I also encountered breaking changes when using pynamodb 4.2.0 and marshmallow 3.3 Looks like 2 things caused the breakage for me:

1. The removal of the MapAttributeMeta class from pynamodb.attributes
2. The inclusion of a new kwarg "ordered" for the SchemaOpts class in marshmallow

Not sure if this is the best solution but I was able to get a local version running by changing the mapping in convert.py to import the MapAttribute class instead of the MapAttributeMeta (I'm not sure what the actual effects of this are I'm mostly just doing this to get past the import error)

PYNAMODB_TYPE_MAPPING = {
    attributes.NumberAttribute: fields.Number,
    attributes.JSONAttribute: fields.Raw,
    attributes.UnicodeAttribute: fields.String,
    attributes.BooleanAttribute: fields.Boolean,
    attributes.UTCDateTimeAttribute: fields.DateTime,
    attributes.MapAttribute: custom_fields.PynamoNested,
    attributes.ListAttribute: fields.List,
    attributes.NullAttribute: fields.Raw,
    attributes.UnicodeSetAttribute: custom_fields.UnicodeSet,
    attributes.NumberSetAttribute: custom_fields.NumberSet
}

Then to get past the second issue I passed in any other args or kwargs to the parent constructor for the ModelOpts in schema.py

class ModelOpts(SchemaOpts):
    def __init__(self, meta, *args, **kwargs):
        SchemaOpts.__init__(self, meta, *args, **kwargs)
        self.model = getattr(meta, 'model', None)

After doing that I was able to do basic round trip serialization with simple objects

[fernandochimi-noverde]

Hello people.

I have the same problem.
Can you have some solution for this issue?

[chrismaille]

Working fork: https://github.com/chrismaille/marshmallow-pynamodb