Nested Optional dataclass parameters require class_path/init_args

[odedbd]

          Another UPDATE:

Seems I was a little too quick to say it works as expected with pure dataclasses. I found one edge cases - when a dataclass parameter is nested inside another dataclass, and it is defined as an Optional field, it requires providing class_path/init_args.

A concrete example -

@dataclass
class Nested:
  f1: str = ''
  f2: int = 1

@dataclass
class Parent:
  fn: Optional[Nested] = None

In the above setup, for the config.yaml for Parent it would have to be

fn:
  class_path: Nested
  init_args:
    f2: 3

If I change Parent making Nested non-Optional, class_path/init_args are no longer needed. If I use the above configuration and do not add class_path/init_args, I get an error like this -

Does not validate against any of the Union subtypes
  Subtypes: (<class 'Nested'>, <class 'NoneType'>)
  Errors:
    - Not a valid Nested
    Subclass types expect one of:
    - a class path (str)
    - a dict with class_path entry
    - a dict without class_path but with init_args entry (class path given previously)
    - Expected a <class 'NoneType'>
  Given value type: <class 'dict'>

Originally posted by @odedbd in #236 (comment)

[mauvilsa]

Support for dataclasses nested in a type, including Optional, was implemented in #267.

[odedbd]

@mauvilsa thanks! I'll check it out.

[odedbd]

@mauvilsa I finally got around to testing this (project was in code-freeze for a while). Seems to working great now, thanks for implementing the clean support for nested optional datalcass parameters.