Adding example request data to path parameters defined through dependency injection

Overview

As heavily discussed in #14. I can't seem to add route example request data to /docs when the path parameters are defined through dependency injection. I thought I'd pull it out to its own issue here to track that progress instead of leaving the PR in purgatory.

Issue

I guess I am having an issue declaring request data examples for specific endpoint/route parameters when said endpoint/route parameters are defined through dependency injection. In the below example, I need to verify that the namespace actually exists prior to returning data about it. To do that, I followed this example in the FastAPI docs. It works great.

However, in /docs, I'd love to give examples for namespaces. To try and do that, I followed this example in the FastAPI docs.

Visiting /docs, however, provides the user with no example request data:

If I comment out the global dependencies like so:

router = APIRouter(
    prefix="/pep/{namespace}",
    # dependencies=[Depends(verify_namespace)],
)

The example is shown. I can also verify that declaring requirements in the Path() instance like min_length or max_length, these requirements are honored by FastAPI (even though I can't see the requirements in /docs).

Code

# main.py
from fastapi import FastAPI, JSONResponse
from .routers import namespace

app = FastAPI()

app.include_router(
    namespace.router
)

# routers/namespace.py
from fastapi import APIRouter, Depends

from ..dependencies import *
from ..main import _PEP_STORES
from ..route_examples import example_namespace

router = APIRouter(
    prefix="/pep/{namespace}",
    dependencies=[Depends(verify_namespace)],
)

@router.get("/", summary="Fetch details about a particular namespace.")
async def get_namespace(namespace: str = example_namespace):
    """Fetch namespace. Returns a JSON representation of the namespace and the projects inside it."""
    return JSONResponse(content=_PEP_STORES[namespace])

# dependencies.py
from .main import _PEP_STORES

def verify_namespace(namespace: str = example_namespace) -> None:
    if namespace not in _PEP_STORES:
        raise HTTPException(status_code=404, detail=f"namespace '{namespace}' not found.")

# route_examples.py
from fastapi import Path

example_namespace = Path(
    ...,
    description="A namespace that holds projects.",
    example="demo",
)

Reproduce the missing example from main.py using routers/namespace.py, dependencies.py, and route_examples.py, keeping the router dependency enabled. Start by inspecting the generated schema behind /docs and compare it with the version without the dependency. Done means the namespace example appears in /docs while dependency-based validation still works.