Improvements to unify the functionality from decorator & Dataclass in a single class

[eos87]

Purpose

The intention to avoid needing to have both a Dataclass and a @dataclass decorator

What has changed

• Introduced DataclassBase for reusable utility methods (to_dict, from_dict, ser_model).
• Added DataclassMeta to handle automatic Pydantic dataclass wrapping and custom Config merging.
• Enabled per-class custom configuration via a Config dictionary in child classes.

Example usage

class RingBearer(Dataclass):
    name: str
    race: str

    # custom configuration that will merge/override default one
    Config = {
        "extra": "allow",
    }

frodo = RingBearer(name="Frodo Baggins", race="Hobbit")

# unexpected fields are allowed due to 'extra': 'allow' (allowed by default, this is just for tests)
frodo.unknown_item = "Mithril Coat" 
frodo.secret_mission = "Destroy the One Ring"

@MarkLark86 following up on our conversation here what do you think? If you think it looks good I'd merge it and replace the usages of the decorator. Also extend the documentation a little bit to make it clear what is the intention.

Thanks for checking!

[BrianMwangi21]

LGTM!

[MarkLark86]

@eos87 How does this work with the IDE predictions/suggestions when typing field names?

[eos87]

@eos87 How does this work with the IDE predictions/suggestions when typing field names?

It does. This is vscode below. I would assume it would also work on PyCharm and others.

[MarkLark86]

Testing this locally, and I found 2 things (1 of those is probably an issue with my original code).

• from_dict and from_json return an instance of dict and not an instance of the class
• mypy fails to recognise arguments to __init__.

from superdesk.core.resources import Dataclass

class Person(Dataclass):
    name: str

assert type(Person(name="Monkeys")) == Person  # True
assert type(Person.from_dict(dict(name="Monkeys"))) == Person  # False
assert type(Person.from_dict(dict(name="Monkeys"))) == dict  # True
assert type(Person.from_json('{"name": "Monkeys"}')) == Person  # False
assert type(Person.from_json('{"name": "Monkeys"}')) == dict  # False

Person(name="Monkeys")  # mypy error: Unexpected keyword argument "name" for "Person"  [call-arg]

Might be good to add some tests with using this new datatype of ours

[eos87]

from_dict and from_json return an instance of dict and not an instance of the class

yeah, it was already a dict indeed. I'll take a look to return the proper model instance.

Person(name="Monkeys") # mypy error: Unexpected keyword argument "name" for "Person" [call-arg]

interesting, I've just tried this locally and it worked for me. Maybe we have a different version of mypy?

[eos87]

Improvements added so editor will autocomplete the attributes inline when creating an instance of a class. Also added some tests to double check the functionality of the utility methods from_dict, from_json, to_dict and to_json.

[MarkLark86]

Looks like a good improvement, thanks mate