How to properly access request param types in handlers where params are documented in parent router?

[cainenielsen]

I am pretty new to Hono so I am assuming I am missing something obvious, but I have exhausted the content on hono.dev trying to understand this so here we go.

My goal is to follow the recommendation of using nested Hono() instances for grouping routes and to support custom parameters in paths; eg. /:someId, which seems to work for handlers set directly on hono instances with basePath() but not on handlers set on child instances using .route(). I assume the context of the request parameter and its type is losted between the two instances.

My questions are as follows...

• Is this a bug that needs to be solved?
• Could this be a feature that should be requested?
• Is there a method, type, or overload that I can use to fix this?
• Is there a better or more common approach to building with Hono that covers this situation and circumvents this issue?

Example:

// parentRouter.ts

import childRouter from './childRouter'

const parentRouter = new Hono().basePath('/:someId')

parentRouter.get('/some-path', async (context) => {
  const someId = context.req.param('someId') // -> ✔️ `const someId: string`
  return context.text(someId)
})

parentRouter.route('/child', childRouter)

// childrouter.ts

const childrouter = new Hono()

childrouter.get('/some-path', async (context) => {
  const someId = context.req.param('someId') // -> ❌ `Argument of type 'string' is not assignable to parameter of type 'never'.ts(2345)`
  return context.text(someId)
})

export default childRouter

Thanks for your time and support.

[cainenielsen]

Ah, I just found a question I believe is similar.
https://github.com/orgs/honojs/discussions/2257

[yusukebe]

Hi @cainenielsen

It is not a bug, nor one we do not plan to address at this time right now. However, it is good to leave it as a feature request while it will be difficult to implement.

The workaround is this:

childrouter.get('/some-path', async (context) => {
  const someId = context.req.param<'/:someId'>('someId')
  return context.text(someId)
})