Allow custom Route export field

[theo-lubert]

Summary

I'm trying to add a export const customConfig = ... to my route.ts (App Router), but Next.js only allows GET, POST, PUT, etc

Type error: Route "app/(server)/api/test/route.ts" does not match the required types of a Next.js Route.
  "customConfig" is not a valid Route export field.

That limitation forces me to have a separate file, that implement everything in exactly the same way, which I then export in route.ts like so:

export { OPTIONS, HEAD, GET, POST, PUT, PATCH, DELETE } from './server'

Which is... annoying I'd say
And I understands why this doesn't work, this not a bug, and it is even documented here (file-conventions/route), but I ask myself: why is it this strict ?

Basically what I'm wondering about is:

• Why do we have this limitation ?
• Is there any way to get around this behavior ? (without disabling Next.js TS plugin entirely)
• Would a PR be welcome to allow this entirely ? (Draft: Allows custom route.ts exports with the "_" prefix #55157)
• or at least one that make it less strict by allowing prefixed kerys (like _test for exemple) ?

Any info on this ?

Source

I found:

• the error message in the code here (typescript/diagnosticFormatter.ts#L89)
• the actual type definition here (webpack/plugins/next-types-plugin/index.ts#L57)

[theo-lubert]

Draft PR: #55157

[theo-lubert]

I changed the category to "Ideas" as I actualy propose a change, with an available PR

[allestaire]

I guess they did not approved the PR, tsk tsk,
Its so confusing why they need to limit ttsk tsk

[theo-lubert]

@allestaire It did not get much attention, and has not been looked at by the team yet.

As of why there is this limitation: I think the goal is to improves the DX by eliminating all possible typos, which is fair. Yet, the _ pattern is used in other parts of Next.js to allow this kind of things, so I think it's still relevant

The fix is actually very simple (PR arleady available), and doesn't interfere with the intended behaviour/goal.
Based on file ownership, maybe one of @timneutkens @ijjk @shuding @huozhi @ztanner @feedthejim could greenlight this ?

[theo-lubert]

I moved the PR from Draft to Open, we'll if it helps or not

[allestaire]

Ahh I see, thanks for the response 😄