feat(client): support fetch headers in link options

apps/content/docs/adapters/next.md

@@ -102,7 +102,7 @@ const link = new RPCLink({
     }
 
     const { headers } = await import('next/headers')
-    return Object.fromEntries(await headers())
+    return await headers()
   },
 })
 ```

apps/content/docs/adapters/nuxt.md

@@ -57,7 +57,7 @@ export default defineNuxtPlugin(() => {
 
   const link = new RPCLink({
     url: `${typeof window !== 'undefined' ? window.location.origin : 'http://localhost:3000'}/rpc`,
-    headers: () => Object.fromEntries(event?.headers ?? []),
+    headers: event?.headers,
   })
 
   const client: RouterClient<typeof router> = createORPCClient(link)

apps/content/docs/adapters/solid-start.md

@@ -61,7 +61,7 @@ import { getRequestEvent } from 'solid-js/web'
 
 const link = new RPCLink({
   url: `${typeof window !== 'undefined' ? window.location.origin : 'http://localhost:3000'}/rpc`,
-  headers: () => Object.fromEntries(getRequestEvent()?.request.headers ?? []),
+  headers: () => getRequestEvent()?.request.headers ?? {},
 })
 ```
 

packages/client/src/adapters/standard/rpc-link-codec.test.ts

@@ -104,6 +104,26 @@ describe('standardRPCLinkCodec', () => {
       expect(request.headers).toBe(mergeStandardHeadersSpy.mock.results[0]!.value)
     })
 
+    it('support fetch headers', async () => {
+      const headers = new Headers()
+      headers.append('cookie', 'a=1')
+      headers.append('cookie', 'b=2')
+      headers.append('set-cookie', 'a1=1')
+      headers.append('set-cookie', 'b1=2')
+
+      const codec = new StandardRPCLinkCodec(serializer, {
+        url: 'http://localhost:3000',
+        headers,
+      })
+
+      const request = await codec.encode(['test'], 'input', { context: {} })
+
+      expect(request.headers).toEqual({
+        'cookie': 'a=1; b=2',
+        'set-cookie': ['a1=1', 'b1=2'],
+      })
+    })
+
     describe('base url', () => {
       it('works with /prefix', async () => {
         const codec = new StandardRPCLinkCodec(serializer, {

packages/client/src/adapters/standard/rpc-link-codec.ts

@@ -6,7 +6,7 @@ import type { StandardLinkCodec } from './types'
 import { isAsyncIteratorObject, stringifyJSON, value } from '@orpc/shared'
 import { mergeStandardHeaders } from '@orpc/standard-server'
 import { createORPCErrorFromJson, isORPCErrorJson, isORPCErrorStatus, ORPCError } from '../../error'
-import { getMalformedResponseErrorCode, toHttpPath } from './utils'
+import { getMalformedResponseErrorCode, toHttpPath, toStandardHeaders } from './utils'
 
 export interface StandardRPCLinkCodecOptions<T extends ClientContext> {
   /**
@@ -39,7 +39,7 @@ export interface StandardRPCLinkCodecOptions<T extends ClientContext> {
   /**
    * Inject headers to the request.
    */
-  headers?: Value<Promisable<StandardHeaders>, [options: ClientOptions<T>, path: readonly string[], input: unknown]>
+  headers?: Value<Promisable<StandardHeaders | Headers>, [options: ClientOptions<T>, path: readonly string[], input: unknown]>
 }
 
 export class StandardRPCLinkCodec<T extends ClientContext> implements StandardLinkCodec<T> {
@@ -61,16 +61,16 @@ export class StandardRPCLinkCodec<T extends ClientContext> implements StandardLi
   }
 
   async encode(path: readonly string[], input: unknown, options: ClientOptions<T>): Promise<StandardRequest> {
+    let headers = toStandardHeaders(await value(this.headers, options, path, input))
+    if (options.lastEventId !== undefined) {
+      headers = mergeStandardHeaders(headers, { 'last-event-id': options.lastEventId })
+    }
+
     const expectedMethod = await value(this.expectedMethod, options, path, input)
-    let headers = await value(this.headers, options, path, input)
     const baseUrl = await value(this.baseUrl, options, path, input)
     const url = new URL(baseUrl)
     url.pathname = `${url.pathname.replace(/\/$/, '')}${toHttpPath(path)}`
 
-    if (options.lastEventId !== undefined) {
-      headers = mergeStandardHeaders(headers, { 'last-event-id': options.lastEventId })
-    }
-
     const serialized = this.serializer.serialize(input)
 
     if (

packages/client/src/adapters/standard/utils.test.ts

@@ -1,11 +1,21 @@
-import { getMalformedResponseErrorCode, toHttpPath } from './utils'
+import { getMalformedResponseErrorCode, toHttpPath, toStandardHeaders } from './utils'
 
 it('convertPathToHttpPath', () => {
   expect(toHttpPath(['ping'])).toEqual('/ping')
   expect(toHttpPath(['nested', 'ping'])).toEqual('/nested/ping')
   expect(toHttpPath(['nested/', 'ping'])).toEqual('/nested%2F/ping')
 })
 
+it('toStandardHeaders', () => {
+  expect(toStandardHeaders({})).toEqual({})
+  expect(toStandardHeaders({ 'content-type': 'application/json' })).toEqual({ 'content-type': 'application/json' })
+
+  expect(toStandardHeaders(new Headers())).toEqual({})
+  const headers = new Headers({ 'content-type': 'application/json' })
+  expect(toStandardHeaders(headers)).toEqual({ 'content-type': 'application/json' })
+  expect(toStandardHeaders({ forEach: headers.forEach.bind(headers) } as any)).toEqual({ 'content-type': 'application/json' })
+})
+
 it('getMalformedResponseErrorCode', () => {
   expect(getMalformedResponseErrorCode(400)).toEqual('BAD_REQUEST')
   expect(getMalformedResponseErrorCode(401)).toEqual('UNAUTHORIZED')

packages/client/src/adapters/standard/utils.ts

@@ -1,10 +1,24 @@
+import type { StandardHeaders } from '@orpc/standard-server'
 import type { HTTPPath } from '../../types'
+import { toStandardHeaders as fetchHeadersToStandardHeaders } from '@orpc/standard-server-fetch'
 import { COMMON_ORPC_ERROR_DEFS } from '../../error'
 
 export function toHttpPath(path: readonly string[]): HTTPPath {
   return `/${path.map(encodeURIComponent).join('/')}`
 }
 
+export function toStandardHeaders(headers: Headers | StandardHeaders): StandardHeaders {
+  /**
+   * Determines if the provided `headers` is a headers-like object.
+   * Avoids `instanceof` checks as this is intended for standard APIs where the Headers constructor may not be available.
+   */
+  if (typeof headers.forEach === 'function') {
+    return fetchHeadersToStandardHeaders(headers as Headers)
+  }
+
+  return headers as StandardHeaders
+}
+
 export function getMalformedResponseErrorCode(status: number): string {
   return Object.entries(COMMON_ORPC_ERROR_DEFS).find(([, def]) => def.status === status)?.[0] ?? 'MALFORMED_ORPC_ERROR_RESPONSE'
 }

packages/openapi-client/src/adapters/standard/openapi-link-codec.test.ts

@@ -50,6 +50,26 @@ describe('standardOpenapiLinkCodecOptions', () => {
       expect(request.headers['x-custom']).toEqual('value')
     })
 
+    it('support fetch headers', async () => {
+      const headers = new Headers()
+      headers.append('cookie', 'a=1')
+      headers.append('cookie', 'b=2')
+      headers.append('set-cookie', 'a1=1')
+      headers.append('set-cookie', 'b1=2')
+
+      const codec = new StandardOpenapiLinkCodec({ ping: oc }, serializer, {
+        url: 'http://localhost:3000',
+        headers,
+      })
+
+      const request = await codec.encode(['ping'], 'input', { context: {} })
+
+      expect(request.headers).toEqual({
+        'cookie': 'a=1; b=2',
+        'set-cookie': ['a1=1', 'b1=2'],
+      })
+    })
+
     describe('inputStructure=compact', () => {
       describe('with dynamic params', () => {
         const codec = new StandardOpenapiLinkCodec({ ping: oc.route({ path: '/ping/{date}' }) }, serializer, {

packages/openapi-client/src/adapters/standard/openapi-link-codec.ts

@@ -5,7 +5,7 @@ import type { Promisable, Value } from '@orpc/shared'
 import type { StandardHeaders, StandardLazyResponse, StandardRequest, StandardResponse } from '@orpc/standard-server'
 import type { StandardOpenAPISerializer } from './openapi-serializer'
 import { createORPCErrorFromJson, isORPCErrorJson, isORPCErrorStatus } from '@orpc/client'
-import { getMalformedResponseErrorCode, toHttpPath } from '@orpc/client/standard'
+import { getMalformedResponseErrorCode, toHttpPath, toStandardHeaders } from '@orpc/client/standard'
 import { fallbackContractConfig, isContractProcedure, ORPCError } from '@orpc/contract'
 import { get, isObject, value } from '@orpc/shared'
 import { mergeStandardHeaders } from '@orpc/standard-server'
@@ -24,7 +24,7 @@ export interface StandardOpenapiLinkCodecOptions<T extends ClientContext> {
   /**
    * Inject headers to the request.
    */
-  headers?: Value<Promisable<StandardHeaders>, [
+  headers?: Value<Promisable<StandardHeaders | Headers>, [
         options: ClientOptions<T>,
         path: readonly string[],
         input: unknown,
@@ -45,13 +45,12 @@ export class StandardOpenapiLinkCodec<T extends ClientContext> implements Standa
   }
 
   async encode(path: readonly string[], input: unknown, options: ClientOptions<T>): Promise<StandardRequest> {
-    const baseUrl = await value(this.baseUrl, options, path, input)
-    let headers = await value(this.headers, options, path, input)
-
+    let headers = toStandardHeaders(await value(this.headers, options, path, input))
     if (options.lastEventId !== undefined) {
       headers = mergeStandardHeaders(headers, { 'last-event-id': options.lastEventId })
     }
 
+    const baseUrl = await value(this.baseUrl, options, path, input)
     const procedure = get(this.contract, path)
 
     if (!isContractProcedure(procedure)) {

packages/standard-server-fetch/src/headers.ts

@@ -5,7 +5,7 @@ import type { StandardHeaders } from '@orpc/standard-server'
  * @param standardHeaders - The base headers can be changed by the function and effects on the original headers.
  */
 export function toStandardHeaders(headers: Headers, standardHeaders: StandardHeaders = {}): StandardHeaders {
-  for (const [key, value] of headers) {
+  headers.forEach((value, key) => {
     if (Array.isArray(standardHeaders[key])) {
       standardHeaders[key].push(value)
     }
@@ -15,7 +15,7 @@ export function toStandardHeaders(headers: Headers, standardHeaders: StandardHea
     else {
       standardHeaders[key] = value
     }
-  }
+  })
 
   return standardHeaders
 }

playgrounds/solid-start/src/lib/orpc.ts

@@ -15,7 +15,7 @@ declare global {
 
 const link = new RPCLink({
   url: `${typeof window !== 'undefined' ? window.location.origin : 'http://localhost:3000'}/rpc`,
-  headers: () => Object.fromEntries(getRequestEvent()?.request.headers ?? []),
+  headers: () => getRequestEvent()?.request.headers ?? {},
 })
 
 export const client: RouterClient<typeof router> = globalThis.$client ?? createORPCClient(link)