feat(typescript) [DRAFT] Add support for discriminated unions in Python v2 generator

[GrantRheingold]

Description

This PR adds support for generating discriminated unions in python using a typescript generator function.

Changes Made

• Constructs appropriate class literal from arbitrary number of classes for creating a union
• Ensures generated code follows Python naming conventions and type safety
• Creates UndiscriminatedUnionGenerator class that generates simple typing.Union types

Future Work

• As discussed, the imports should be prefixed by the package to avoid cross-module confusion between imported packages. So the final implementation should have typing.Union[...] instead of from typing import Union ... Union[...]

Testing

• Manual testing completed

Tested by running

pnpm seed test --generator pydantic-v2 --log-level debug --fixture exhaustive --skip-scripts --exhaustive

and comparing the output to the generated output of the python-native generated file here.

from typing import Union, Literal
from typing_extensions import Literal as TypingExtensionsLiteral
from .dog import Dog
from .cat import Cat

class Animal_Dog(Dog):
    animal: Literal["dog"]
    class Config:
        allow_population_by_field_name = True


class Animal_Cat(Cat):
    animal: Literal["cat"]
    class Config:
        allow_population_by_field_name = True


Animal = Union[Animal_Dog, Animal_Cat]

[graphite-app]

The code adds a field with a Literal type but is missing the required import. Please add the following import after the Union import:

file.addReference(python.reference({ name: "Literal", modulePath: ["typing"] }));

This will ensure the generated Python code has all necessary imports for the discriminated union implementation.

Suggested change

	file.addReference(python.reference({ name: "Union", modulePath: ["typing"] }));
	file.addReference(python.reference({ name: "Union", modulePath: ["typing"] }));
	file.addReference(python.reference({ name: "Literal", modulePath: ["typing"] }));

Spotted by Diamond

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