0.137.0: how to get all paths of a router?

[davidbrochart]

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Example Code

for route in router.routes:
   route.path  # the `path` attribute may not exist

Description

In Jupyverse we check for path conflicts in plugins here, and this started to fail with v0.137.0.

Operating System

Linux

Operating System Details

Ubuntu 26.04.

FastAPI Version

0.137.0

Pydantic Version

2.13.4

Python Version

3.14

Additional Context

No response

[davidbrochart]

This is the kind of code that we have to write: jupyter-server/jupyverse@63b242e.
Maybe that should be provided by FastAPI?

[joshvarcheesy]

Tacking on to this discussion as I'm facing the same issue.

The most-referenced version of this pattern is in starlette-prometheus and copied into many internal observability libraries:

from starlette.middleware.base import BaseHTTPMiddleware
from starlette.routing import Match


class PrometheusMiddleware(BaseHTTPMiddleware):
    async def dispatch(self, request, call_next):
        method = request.method
        path_template, is_handled = self.get_path_template(request)
        # ... record request count / latency / etc. labeled by `path_template` ...
        return await call_next(request)

    @staticmethod
    def get_path_template(request):
        for route in request.app.routes:
            match, _ = route.matches(request.scope)
            if match == Match.FULL:
                return route.path, True
        return request.url.path, False

The label path_template is load-bearing: it must be the templated form (/items/{item_id}) rather than the concrete URL (/items/123), or every distinct request path becomes a unique Prometheus counter row → unbounded label cardinality → memory exhaustion in the Prometheus server.

Pre-0.137 this worked because include_router flattened children into individual APIRoute entries on the parent.

[joshvarcheesy]

one work around is using _iter_included_route_candidates
for route in _iter_included_route_candidates(request.app.routes): # pyright: ignore[reportAny] match, _ = route.matches(request.scope) if match == Match.FULL:
Will want confirmation this is fine/ making this public.

[kamikaze]

same here. ai slop?