[BUG] Annotating the request of a paginated route crashes

[Jonesus]

Describe the bug

When annotating the request parameter of a route (in order to type request.auth) that has been decorated with @paginate the django server crashes with the following exception:

  File "/app/.venv/lib/python3.10/site-packages/ninja/router.py", line 268, in decorator
    self.add_api_operation(
  File "/app/.venv/lib/python3.10/site-packages/ninja/router.py", line 319, in add_api_operation
    path_view.add_operation(
  File "/app/.venv/lib/python3.10/site-packages/ninja/operation.py", line 426, in add_operation
    operation = OperationClass(
  File "/app/.venv/lib/python3.10/site-packages/ninja/operation.py", line 82, in __init__
    self.signature = ViewSignature(self.path, self.view_func)
  File "/app/.venv/lib/python3.10/site-packages/ninja/signature/details.py", line 48, in __init__
    self.signature = get_typed_signature(self.view_func)
  File "/app/.venv/lib/python3.10/site-packages/ninja/signature/utils.py", line 38, in get_typed_signature
    typed_params = [
  File "/app/.venv/lib/python3.10/site-packages/ninja/signature/utils.py", line 43, in <listcomp>
    annotation=get_typed_annotation(param, globalns),
  File "/app/.venv/lib/python3.10/site-packages/ninja/signature/utils.py", line 54, in get_typed_annotation
    annotation = make_forwardref(annotation, globalns)
  File "/app/.venv/lib/python3.10/site-packages/ninja/signature/utils.py", line 60, in make_forwardref
    return evaluate_forwardref(forward_ref, globalns, globalns)
  File "/app/.venv/lib/python3.10/site-packages/ninja/signature/utils.py", line 20, in evaluate_forwardref
    return cast(Any, type_)._evaluate(globalns, localns, recursive_guard=set())
  File "/home/app/.local/share/uv/python/cpython-3.10.8-linux-x86_64-gnu/lib/python3.10/typing.py", line 694, in _evaluate
    eval(self.__forward_code__, globalns, localns),
  File "<string>", line 1, in <module>
NameError: name 'AuthenticatedNinjaRequest' is not defined

This can be reproduced with the following minimal route:

from ninja.pagination import paginate
from django.http import HttpRequest

class AuthenticatedNinjaRequest(HttpRequest):
    auth: User

@api.get('/users', response=List[UserSchema])
@paginate
def list_users(request: AuthenticatedNinjaRequest):
    if request.auth:
        return User.objects.all()
    return User.objects.none()

If the pagination decorator is removed, no crash occurs and everything works as expected.

Potential remedy

The crashing can be fixed by patching the function get_typed_signature at ninja/signature/utils.py with:

def get_typed_signature(call: Callable[..., Any]) -> inspect.Signature:
    "Finds call signature and resolves all forwardrefs"
    signature = inspect.signature(call)
    globalns = getattr(call, "__globals__", {})
    typed_params = [
        inspect.Parameter(
            name=param.name,
            kind=param.kind,
            default=param.default,
            annotation=get_typed_annotation(param, globalns),
        )
        # NOTE: the following line has been changed below
        #                                          vvvvvvvvvvvvvvvvvvvvvvvvvv
        for param in signature.parameters.values() if param.name != "request"
    ]
    typed_signature = inspect.Signature(typed_params)
    return typed_signature

But I'm not certain if this is a good solution. I can submit the above patch as a PR if you think it is sufficient, or if you have some other approach in mind I can try that too.

The only somewhat related issue/PR I could find: #1026

Versions (please complete the following information):

• Python version: 3.10.8
• Django version: 5.1.3
• Django-Ninja version: 1.3.0
• Pydantic version: 2.9.1