fix(trpc-server): auto-detect endpoint from route path (#1599)

* fix(trpc-server): auto-detect endpoint from route path

* add changeset

* bump zod

Author: yusukebe

.changeset/crazy-cougars-follow.md

@@ -0,0 +1,5 @@
+---
+'@hono/trpc-server': patch
+---
+
+fix: auto-detect endpoint from route path

packages/trpc-server/package.json

@@ -49,7 +49,7 @@
     "tsdown": "^0.15.9",
     "typescript": "^5.8.2",
     "vitest": "^3.2.4",
-    "zod": "^3.20.2"
+    "zod": "^4.0.5"
   },
   "engines": {
     "node": ">=16.0.0"

packages/trpc-server/src/index.test.ts

@@ -29,8 +29,7 @@ describe('tRPC Adapter Middleware', () => {
       input: JSON.stringify({ '0': 'Hono' }),
       batch: '1',
     })
-    const req = new Request(`http://localhost/trpc/hello?${searchParams.toString()}`)
-    const res = await app.request(req)
+    const res = await app.request(`/trpc/hello?${searchParams.toString()}`)
     expect(res.status).toBe(200)
     expect(await res.json()).toEqual([
       {
@@ -40,4 +39,43 @@ describe('tRPC Adapter Middleware', () => {
       },
     ])
   })
+
+  it('Should auto-detect endpoint from /v1/* route', async () => {
+    const app = new Hono()
+    app.use('/v1/*', trpcServer({ router: appRouter }))
+
+    const searchParams = new URLSearchParams({
+      input: JSON.stringify({ '0': 'World' }),
+      batch: '1',
+    })
+    const res = await app.request(`/v1/hello?${searchParams.toString()}`)
+    expect(res.status).toBe(200)
+    expect(await res.json()).toEqual([{ result: { data: 'Hello World' } }])
+  })
+
+  it('Should handle short path prefixes like /v/*', async () => {
+    const app = new Hono()
+    app.use('/v/*', trpcServer({ router: appRouter }))
+
+    const searchParams = new URLSearchParams({
+      input: JSON.stringify({ '0': 'Test' }),
+      batch: '1',
+    })
+    const res = await app.request(`/v/hello?${searchParams.toString()}`)
+    expect(res.status).toBe(200)
+    expect(await res.json()).toEqual([{ result: { data: 'Hello Test' } }])
+  })
+
+  it('Should respect explicit endpoint parameter', async () => {
+    const app = new Hono()
+    app.use('/api/trpc/*', trpcServer({ router: appRouter, endpoint: '/api/trpc' }))
+
+    const searchParams = new URLSearchParams({
+      input: JSON.stringify({ '0': 'Explicit' }),
+      batch: '1',
+    })
+    const res = await app.request(`/api/trpc/hello?${searchParams.toString()}`)
+    expect(res.status).toBe(200)
+    expect(await res.json()).toEqual([{ result: { data: 'Hello Explicit' } }])
+  })
 })

packages/trpc-server/src/index.ts

@@ -5,6 +5,7 @@ import type {
 } from '@trpc/server/adapters/fetch'
 import { fetchRequestHandler } from '@trpc/server/adapters/fetch'
 import type { Context, MiddlewareHandler } from 'hono'
+import { routePath } from 'hono/route'
 
 type tRPCOptions = Omit<
   FetchHandlerRequestOptions<AnyRouter>,
@@ -18,22 +19,35 @@ type tRPCOptions = Omit<
   }
 
 export const trpcServer = ({
-  endpoint = '/trpc',
+  endpoint,
   createContext,
   ...rest
 }: tRPCOptions): MiddlewareHandler => {
   const bodyProps = new Set(['arrayBuffer', 'blob', 'formData', 'json', 'text'] as const)
   type BodyProp = typeof bodyProps extends Set<infer T> ? T : never
   return async (c) => {
     const canWithBody = c.req.method === 'GET' || c.req.method === 'HEAD'
+
+    // Auto-detect endpoint from route path if not explicitly provided
+    let resolvedEndpoint = endpoint
+    if (!endpoint) {
+      const path = routePath(c)
+      if (path) {
+        // Remove wildcard suffix (e.g., "/v1/*" -> "/v1")
+        resolvedEndpoint = path.replace(/\/\*+$/, '') || '/trpc'
+      } else {
+        resolvedEndpoint = '/trpc'
+      }
+    }
+
     const res = fetchRequestHandler({
       ...rest,
       createContext: async (opts) => ({
         ...(createContext ? await createContext(opts, c) : {}),
         // propagate env by default
         env: c.env,
       }),
-      endpoint,
+      endpoint: resolvedEndpoint!,
       req: canWithBody
         ? c.req.raw
         : new Proxy(c.req.raw, {

yarn.lock

@@ -2389,7 +2389,7 @@ __metadata:
     tsdown: "npm:^0.15.9"
     typescript: "npm:^5.8.2"
     vitest: "npm:^3.2.4"
-    zod: "npm:^3.20.2"
+    zod: "npm:^4.0.5"
   peerDependencies:
     "@trpc/server": ^10.10.0 || >11.0.0-rc
     hono: ">=4.0.0"
@@ -17320,7 +17320,7 @@ __metadata:
   languageName: node
   linkType: hard
 
-"zod@npm:^3.20.2, zod@npm:^3.22.3":
+"zod@npm:^3.22.3":
   version: 3.24.2
   resolution: "zod@npm:3.24.2"
   checksum: 10c0/c638c7220150847f13ad90635b3e7d0321b36cce36f3fc6050ed960689594c949c326dfe2c6fa87c14b126ee5d370ccdebd6efb304f41ef5557a4aaca2824565