Upgrade to marshmallow 3

[sloria]

👋 Just dropping by to let you know that marshmallow v3 is released.

Upgrading will provide a few benefits for this project:

• You can get rid of places where load_from and dump_to match, since they've been merged into a single parameter, data_key.

https://github.com/microsoft/DLWorkspace/blob/bb8ee5bf460a754be0966703b623dae79f5dfe70/src/ClusterManager/job.py#L152

You could even do automatic camel-casing using this snippet: https://marshmallow.readthedocs.io/en/latest/examples.html#inflection-camel-casing-keys

• You can use the improved fields.Dict to validate the type of keys and values: https://marshmallow.readthedocs.io/en/stable/api_reference.html#marshmallow.fields.Dict
• Performance is significantly improved compared to v2

After skimming the codebase, it looks like the migration will be straightforward.

• Replace usages of load_from and dump_to with data_key.
• Update call sites of JobSchema.load[s] to expect the deserialized data as the return value instead of a tuple. Instead of getting the errors from a tuple, handle ValidationErrors.

from marshmallow import ValidationError

try:
    job_object = JobSchema.load(job)
except ValidationError as error:
    errors = error.messages

[hongzhili]

Thanks! Add @xudifsd

[xudifsd]

Oh, this requires python>=3.5, we will update the code after we migrate to python3, thanks.

[KeironO]

I would love to do this, but there doesn't seem to be any meaningful documentation surrounding how best I can contribute.