From 3a8e066d577bfb7d9645467aa27c08655904f30d Mon Sep 17 00:00:00 2001
From: unnoq <contact@unnoq.com>
Date: Fri, 6 Jun 2025 15:33:37 +0700
Subject: [PATCH] feat(server): inferRPCMethodFromRouter util

---
 packages/client/src/utils.ts                  |  2 +-
 .../server/src/adapters/standard/utils.ts     |  2 +-
 packages/server/src/index.ts                  |  1 +
 packages/server/src/link-utils.test-d.ts      | 10 +++++++
 packages/server/src/link-utils.test.ts        | 24 +++++++++++++++++
 packages/server/src/link-utils.ts             | 26 +++++++++++++++++++
 6 files changed, 63 insertions(+), 2 deletions(-)
 create mode 100644 packages/server/src/link-utils.test-d.ts
 create mode 100644 packages/server/src/link-utils.test.ts
 create mode 100644 packages/server/src/link-utils.ts

diff --git a/packages/client/src/utils.ts b/packages/client/src/utils.ts
index 6417190bd..1775d0d74 100644
--- a/packages/client/src/utils.ts
+++ b/packages/client/src/utils.ts
@@ -45,6 +45,6 @@ export async function safe<TOutput, TError = ThrowableError>(promise: ClientProm
 export function resolveFriendlyClientOptions<T extends ClientContext>(options: FriendlyClientOptions<T>): ClientOptions<T> {
   return {
     ...options,
-    context: options?.context ?? {} as T, // Context only optional if all fields are optional
+    context: options.context ?? {} as T, // Context only optional if all fields are optional
   }
 }
diff --git a/packages/server/src/adapters/standard/utils.ts b/packages/server/src/adapters/standard/utils.ts
index bdd82dbcb..b3c6bbd8d 100644
--- a/packages/server/src/adapters/standard/utils.ts
+++ b/packages/server/src/adapters/standard/utils.ts
@@ -8,6 +8,6 @@ export type FriendlyStandardHandleOptions<T extends Context> =
 export function resolveFriendlyStandardHandleOptions<T extends Context>(options: FriendlyStandardHandleOptions<T>): StandardHandleOptions<T> {
   return {
     ...options,
-    context: options?.context ?? {} as T, // Context only optional if all fields are optional
+    context: options.context ?? {} as T, // Context only optional if all fields are optional
   }
 }
diff --git a/packages/server/src/index.ts b/packages/server/src/index.ts
index 6d9e7e6b9..d53c855e5 100644
--- a/packages/server/src/index.ts
+++ b/packages/server/src/index.ts
@@ -7,6 +7,7 @@ export * from './implementer'
 export * from './implementer-procedure'
 export * from './implementer-variants'
 export * from './lazy'
+export * from './link-utils'
 export * from './middleware'
 export * from './middleware-decorated'
 export * from './middleware-utils'
diff --git a/packages/server/src/link-utils.test-d.ts b/packages/server/src/link-utils.test-d.ts
new file mode 100644
index 000000000..64309f971
--- /dev/null
+++ b/packages/server/src/link-utils.test-d.ts
@@ -0,0 +1,10 @@
+import { RPCLink } from '@orpc/client/fetch'
+import { router } from '../tests/shared'
+import { inferRPCMethodFromRouter } from './link-utils'
+
+it('inferRPCMethodFromContractRouter', () => {
+  const link = new RPCLink({
+    url: 'http://localhost:3000/rpc',
+    method: inferRPCMethodFromRouter(router),
+  })
+})
diff --git a/packages/server/src/link-utils.test.ts b/packages/server/src/link-utils.test.ts
new file mode 100644
index 000000000..c2fd8d19f
--- /dev/null
+++ b/packages/server/src/link-utils.test.ts
@@ -0,0 +1,24 @@
+import { os } from './builder'
+import { inferRPCMethodFromRouter } from './link-utils'
+
+it('inferRPCMethodFromRouter', async () => {
+  const method = inferRPCMethodFromRouter({
+    head: os.route({ method: 'HEAD' }).handler(() => {}),
+    get: os.route({ method: 'GET' }).handler(() => { }),
+    post: os.route({}).handler(() => { }),
+    nested: os.lazy(() => Promise.resolve({
+      default: {
+        get: os.lazy(() => Promise.resolve({ default: os.route({ method: 'GET' }).handler(() => { }) })),
+        delete: os.route({ method: 'DELETE' }).handler(() => { }),
+      },
+    })),
+  })
+
+  expect(await method({}, ['head'])).toBe('GET')
+  expect(await method({}, ['get'])).toBe('GET')
+  expect(await method({}, ['post'])).toBe('POST')
+  expect(await method({}, ['nested', 'get'])).toBe('GET')
+  expect(await method({}, ['nested', 'delete'])).toBe('DELETE')
+
+  await expect(method({}, ['nested', 'not-exist'])).rejects.toThrow(/No valid procedure found at path/)
+})
diff --git a/packages/server/src/link-utils.ts b/packages/server/src/link-utils.ts
new file mode 100644
index 000000000..67e88854a
--- /dev/null
+++ b/packages/server/src/link-utils.ts
@@ -0,0 +1,26 @@
+import type { HTTPMethod } from '@orpc/client'
+import type { AnyRouter } from './router'
+import { fallbackContractConfig } from '@orpc/contract'
+import { unlazy } from './lazy'
+import { isProcedure } from './procedure'
+import { getRouter } from './router-utils'
+
+/**
+ * Help RPCLink automatically send requests using the specified HTTP method in the router.
+ */
+export function inferRPCMethodFromRouter(router: AnyRouter): (options: unknown, path: readonly string[]) => Promise<Exclude<HTTPMethod, 'HEAD'>> {
+  return async (_, path) => {
+    const { default: procedure } = await unlazy(getRouter(router, path))
+
+    if (!isProcedure(procedure)) {
+      throw new Error(
+        `[inferRPCMethodFromRouter] No valid procedure found at path "${path.join('.')}". `
+        + `This may happen when the router is not properly configured.`,
+      )
+    }
+
+    const method = fallbackContractConfig('defaultMethod', procedure['~orpc'].route.method)
+
+    return method === 'HEAD' ? 'GET' : method
+  }
+}