Register middleware after routing, routePath(c, -1) are error

[seepine]

What version of Hono are you using?

4.11.3

What runtime/platform is your app running on? (with version if possible)

Bun

What steps can reproduce the bug?

const app = new Hono()

app.use(async (c, next) => {
  console.log(`[middleware A] in`, c.req.path, routePath(c), routePath(c, -1))
  await next()
  console.log(`[middleware A] out`)
})

app.get('/health', (c) => {
  return c.json({
    status: 'ok',
  })
})

// Register middleware after `/health`
app.use(async (c, next) => {
  console.log(`[middleware B] in`, c.req.path, routePath(c), routePath(c, -1))
  await next()
  console.log(`[middleware B] out`)
})

const server = Bun.serve({
  port: process.env.PORT ?? 3000,
  fetch: app.fetch,
})

And got /*, whether routePath(c, -1) or routePath(c)

[middleware A] in /health /* /*
[middleware A] out

What is the expected behavior?

can got /health

What do you see instead?

got /*

Additional information

No response

[tshmieldev]

This is in fact correct behavior. As docs say, the second argument of the routePath is similar to Array.prototype.at()
The underlying 'array' is in fact
/* -> index 0, from the middleware A
/health -> index 1, from the /health handler
/* -> index 2, from the middleware B

when you do routePath(c, -1), you get the LAST entry, from middleware B, which is /*

You were expecting to get /health.
You can get it by doing:

• routePath(c, -1)
• routePath(c, 1)

Just because you don't reach middleware B in your handler does not mean it is not matched. After all, you could call next() from the handler.

Hope this clarifies the matter for you.

Relevant docs mentioned: https://hono.dev/docs/helpers/route#using-with-index-parameter-1

@seepine

[seepine]

@tshmieldev
How should I obtain the actual route? I don't care about the coordinates of the route, I just need to obtain the actual route.

[tshmieldev]

@seepine
There is no such thing as actual route from hono's perspective. However, those approaches should work:

1. Just use index -2 as the argument. Unless you add middleware after the handler, this will work.

2. Write a custom matching function on r.req.path

3. matchedRoutes() returns an array of objects with a handler field. That field is a reference to the handling function. You can construct a set of handlers of what you consider "actual routes", and see if that handler (the field of the areay entry) is in that set. Then use the path field of that same entry.

Since the issue was not a bug, consider closing / editing this issue. Also see your open issue on a memleak, I have gotten some relevant results there.

[seepine]

@tshmieldev
I am writing a middleware that requires obtaining the real path. I am not sure if it is -1 or -2 in the middleware, at present, I can only obtain it through the routePath method.

As described in this issue, middleware B does not affect the /health handler, but it does affect the routePath acquisition in middleware A, this seems to be a problem.

[tshmieldev]

@seepine
What would happen if you called next() in /health?

[seepine]

@tshmieldev

Like this? I don't understand.

app.get('/health', (c) => {
  // await next() ?
  return c.json({
    status: 'ok',
  })
})

[tshmieldev]

Yes, but instead of (c) you'd need (c, next)

[seepine]

@tshmieldev

app.get('/health', async (c, next) => {
  await next()
  return c.json({
    pid: process.pid,
    status: 'ok',
  })
})

But got

[middleware A] in /health /* /*
[middleware B] in /health /* /*
[middleware B] out
[middleware A] out

And it seems inappropriate because I need to intercept based on the path in the middleware, and sometimes it doesn't even enter /health at all.

[seepine]

For example, if I want to implement a request path blacklist middleware, i got route path /* and I cannot determine if it is on the path blacklist.

[tshmieldev]

@seepine
See how middleware B is called when you next() in /health?

That's how middleware and route matching works. Middleware B is matched to /health, because you could do next().
This is 100% normal and anticipated behavior. That is why routePath(c, -1) returned /*. Because of Middleware B that could have been called.

If you want to implement a blocklist, I again recommend the methods I mentioned in my initial reply. See the docs on matchedRoutes method:
https://hono.dev/docs/helpers/route#matchedroutes

Additionally,
Using Array.prototype.some() on the array returned from matchedRoutes may be a decent and clean option.