feat: add typevar expansion

[harryle95]

Description

Add a method for typevar expansion on registration
This allows the use of generic route handler and generic controller without relying on forward references.

Closes #3206

A self-contained example - which would fail in the previous version:

from dataclasses import dataclass, field
from typing import Generic, TypeVar
from uuid import UUID, uuid4

from litestar import Controller, Litestar, Router, post


@dataclass
class BookDataClass:
    title: str
    id: UUID = field(default_factory=uuid4)


@dataclass
class AuthorDataClass:
    title: str
    id: UUID = field(default_factory=uuid4)


T = TypeVar("T")


class GenericController(Controller, Generic[T]):
    model_class: T

    def __class_getitem__(cls, model_class: type) -> type:
        cls_dict = {"model_class": model_class}
        return type(f"GenericController[{model_class.__name__}", (cls,), cls_dict)

    def __init__(self, owner: Router) -> None:
        super().__init__(owner)
        self.signature_namespace[T] = self.model_class  

class BaseController(GenericController[T]):
    @post()
    async def create(self, data: T) -> T:  
        return data


class AuthorDataClassController(BaseController[AuthorDataClass]):
    path = "/AuthorDataClass"


class BookDataClassController(BaseController[BookDataClass]):
    path = "/BookDataClass"
    signature_namespace = {"S": int, "U": float}


app = Litestar([AuthorDataClassController, BookDataClassController])

All failed tests were not caused by this new update. Please let me know what you think.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 98.25%. Comparing base (4b79615) to head (95d20c4).

Additional details and impacted files

@@           Coverage Diff            @@
##           develop    #3242   +/-   ##
========================================
  Coverage    98.25%   98.25%           
========================================
  Files          322      322           
  Lines        14666    14670    +4     
  Branches      2333     2334    +1     
========================================
+ Hits         14410    14414    +4     
  Misses         116      116           
  Partials       140      140           

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[JacobCoffee]

Suggested change

	"""Expand TypeVar for any parameters in type_hint
	Args:
	type_hint: mapping of parameter to type obtained from calling `get_type_hints` or `get_fn_type_hints`
	namespace: mapping of TypeVar to concrete type
	Returns:
	type_hint with any TypeVar parameter expanded
	"""
	"""Expand :class:`~typing.TypeVar` for any parameters in ``type_hint``
	Args:
	type_hint: mapping of parameter to type obtained from calling ``get_type_hints`` or ``get_fn_type_hints``
	namespace: mapping of :class:`~typing.TypeVar` to concrete type
	Returns:
	``type_hint`` with any :class:`~typing.TypeVar` parameter expanded
	"""

[guacs]

Thanks @haryle! This is a cool change.

[peterschutt]

Thanks @haryle - LGTM!

One nit, can we please not add arbitrary style changes - there are a few cases of added line wraps for imports that would otherwise be lines untouched by the PR. Perhaps you have some global formatter settings that conflict with ours?

Cheers

[peterschutt]

Please limit the changes to those necessary for the PR.

[harryle95]

Yeah, all the import formating changes were done by my linter. I will reformat them.

[peterschutt]

.

[guacs]

I think this is good to go after the comments by @peterschutt has been resolved :)

[github-actions]

Documentation preview will be available shortly at https://litestar-org.github.io/litestar-docs-preview/3242

[peterschutt]

Thanks!

[JacobCoffee]

@all-contributors add @haryle code tests

[allcontributors]

@JacobCoffee

I've put up a pull request to add @haryle! 🎉