Any way to modify the request path in middleware?

[kornysietsma]

I am trying to replicate a legacy API which had optional versions in paths, so GET /v1/foo actually called GET /foo under the covers.

I was hoping to add some middleware that just intercepted paths starting with /v1 and removed the prefix (or re-directed somehow to the correct route) - but it seems that modifying the ctx.req.path does nothing.

Is this possible? I've seen examples that clone ctx.req.raw and make a brand new request - that feels a bit ugly, and I'm not sure that Hono will use the new request's path for routing anyway.

Any suggestions? (for added complexity we are using the zod-openapi middleware so I can't just give our routes both /foo and /v1/foo paths easily. And we'd like to decrement the /v1 rubbish anyway, so I'd prefer to not have it in our openapi schema)

[goisaki]

How about using redirect() to handle access to legacy API endpoints?

import { Hono } from 'hono'

const app = new Hono()

app.get('/api/hello', (c) => {
  return c.text('api')
})

app.use('/api/v1/*', async (c) => {
  const newPath = c.req.path.replace(/^\/api\/v1/, '/api');
  // 301 means redirect-permanently
  return c.redirect(newPath)
})

This avoids setting up legacy APIs one at a time.
Including the version in the API path is a safe way to manage breaking changes, so decide carefully whether to use it.

[kornysietsma]

sadly that only works if our external clients all respect 301 redirect and I'm not totally confident they do.
What we decided on was to move to hono v4 and just specify multiple paths. (and we ditched the hod-zono-openapi stuff so we can hide the /v1 from our schema)

Our resulting code:

  app.on('GET', ['/foo', '/v1/foo'],

Not as generic as a middleware for all routes - but a lot less work.