Merge pull request #1535 from MarcelOlsen/fix/sse-response-validation

fix: skip response validation for generators and streams

Author: SaltyAom

src/compose.ts

@@ -267,7 +267,7 @@ const composeValidationFactory = ({
 			`c.set.status=${name}.code\n` +
 			`${name}=${name}.response` +
 			`}` +
-			`if(${name} instanceof Response === false)` +
+			`if(${name} instanceof Response === false && typeof ${name}?.next !== 'function' && !(${name} instanceof ReadableStream))` +
 			`switch(c.set.status){`
 
 		for (const [status, value] of Object.entries(validator.response!)) {

test/validator/response.test.ts

@@ -1,4 +1,6 @@
-import { Elysia, t } from '../../src'
+import { Elysia, t, sse } from '../../src'
+import { streamResponse } from '../../src/adapter/utils'
+import * as z from 'zod'
 
 import { describe, expect, it } from 'bun:test'
 import { post, req, upload } from '../utils'
@@ -450,4 +452,114 @@ describe('Response Validator', () => {
 		const res = await app.handle(req('/'))
 		expect(res.status).toBe(200)
 	})
+
+	it('validate SSE response with generator', async () => {
+		const app = new Elysia().get(
+			'/',
+			function* () {
+				yield sse({ data: { name: 'Alice' } })
+				yield sse({ data: { name: 'Bob' } })
+			},
+			{
+				response: t.Object({
+					data: t.Object({
+						name: t.String()
+					})
+				})
+			}
+		)
+
+		const res = await app.handle(req('/'))
+		expect(res.status).toBe(200)
+		expect(res.headers.get('content-type')).toBe('text/event-stream')
+
+		// Verify the stream contains the expected SSE data
+		const result = []
+		for await (const chunk of streamResponse(res)) {
+			result.push(chunk)
+		}
+
+		expect(result.join('')).toContain('data: {"name":"Alice"}')
+		expect(result.join('')).toContain('data: {"name":"Bob"}')
+	})
+
+	it('validate async SSE response with generator', async () => {
+		const app = new Elysia().get(
+			'/',
+			async function* () {
+				yield sse({ data: { name: 'Charlie' } })
+				await Bun.sleep(1)
+				yield sse({ data: { name: 'Diana' } })
+			},
+			{
+				response: t.Object({
+					data: t.Object({
+						name: t.String()
+					})
+				})
+			}
+		)
+
+		const res = await app.handle(req('/'))
+		expect(res.status).toBe(200)
+		expect(res.headers.get('content-type')).toBe('text/event-stream')
+	})
+
+	it('validate streaming response with generator', async () => {
+		const app = new Elysia().get(
+			'/',
+			function* () {
+				yield { message: 'first' }
+				yield { message: 'second' }
+			},
+			{
+				response: t.Object({
+					message: t.String()
+				})
+			}
+		)
+
+		const res = await app.handle(req('/'))
+		expect(res.status).toBe(200)
+
+		const result = []
+		for await (const chunk of streamResponse(res)) {
+			result.push(chunk)
+		}
+
+		expect(result.join('')).toContain('"message":"first"')
+		expect(result.join('')).toContain('"message":"second"')
+	})
+
+	it('validate SSE with Zod schema (bug report scenario)', async () => {
+		// This test reproduces the exact bug report:
+		// https://github.com/elysiajs/elysia/issues/1490
+		const Schema = z.object({
+			data: z.object({
+				name: z.string()
+			})
+		})
+
+		const app = new Elysia().get(
+			'/',
+			function* () {
+				yield sse({ data: { name: 'Name' } })
+			},
+			{ response: Schema }
+		)
+
+		const res = await app.handle(req('/'))
+
+		// Should not throw validation error
+		expect(res.status).toBe(200)
+		expect(res.headers.get('content-type')).toBe('text/event-stream')
+
+		// Verify the stream contains the expected SSE data
+		const result = []
+		for await (const chunk of streamResponse(res)) {
+			result.push(chunk)
+		}
+
+		expect(result.join('')).toContain('data: {"name":"Name"}')
+	})
 })