feat (ai/core): add toJsonResponse to generateObject result. (#2033)

Author: lgrammel

.changeset/shy-turkeys-jump.md

@@ -0,0 +1,5 @@
+---
+'ai': patch
+---
+
+feat (ai/core): add toJsonResponse to generateObject result.

content/docs/07-reference/ai-sdk-core/03-generate-object.mdx

@@ -373,6 +373,12 @@ console.log(JSON.stringify(object, null, 2));
       description:
         'Warnings from the model provider (e.g. unsupported settings).',
     },
+    {
+      name: 'toJsonResponse',
+      type: '(init?: ResponseInit) => Response',
+      description:
+        'Converts the object to a JSON response. The response will have a status code of 200 and a content type of `application/json; charset=utf-8`.',
+    },
   ]}
 />
 

content/examples/02-next-pages/01-basics/03-generating-object.mdx

@@ -86,7 +86,7 @@ import { z } from 'zod';
 export async function POST(req: Request) {
   const { prompt }: { prompt: string } = await req.json();
 
-  const { object } = await generateObject({
+  const result = await generateObject({
     model: openai('gpt-4'),
     system: 'You generate three notifications for a messages app.',
     prompt,
@@ -101,7 +101,7 @@ export async function POST(req: Request) {
     }),
   });
 
-  return Response.json({ object });
+  return result.toJsonResponse();
 }
 ```
 

packages/core/core/generate-object/generate-object.test.ts

@@ -1,3 +1,4 @@
+import { convertReadableStreamToArray } from '@ai-sdk/provider-utils/test';
 import assert from 'node:assert';
 import { z } from 'zod';
 import { MockLanguageModelV1 } from '../test/mock-language-model-v1';
@@ -84,3 +85,36 @@ describe('result.object', () => {
     assert.deepStrictEqual(result.object, { content: 'Hello, world!' });
   });
 });
+
+describe('result.toJsonResponse', () => {
+  it('should return JSON response', async () => {
+    const result = await generateObject({
+      model: new MockLanguageModelV1({
+        doGenerate: async ({ prompt, mode }) => {
+          return {
+            ...dummyResponseValues,
+            text: `{ "content": "Hello, world!" }`,
+          };
+        },
+      }),
+      schema: z.object({ content: z.string() }),
+      mode: 'json',
+      prompt: 'prompt',
+    });
+
+    const response = result.toJsonResponse();
+
+    assert.strictEqual(response.status, 200);
+    assert.strictEqual(
+      response.headers.get('Content-Type'),
+      'application/json; charset=utf-8',
+    );
+
+    assert.deepStrictEqual(
+      await convertReadableStreamToArray(
+        response.body!.pipeThrough(new TextDecoderStream()),
+      ),
+      ['{"content":"Hello, world!"}'],
+    );
+  });
+});

packages/core/core/generate-object/generate-object.ts

@@ -11,6 +11,7 @@ import { CallWarning, FinishReason, LanguageModel, LogProbs } from '../types';
 import { convertZodToJSONSchema } from '../util/convert-zod-to-json-schema';
 import { retryWithExponentialBackoff } from '../util/retry-with-exponential-backoff';
 import { injectJsonSchemaIntoSystem } from './inject-json-schema-into-system';
+import { prepareResponseHeaders } from '../util/prepare-response-headers';
 
 /**
 Generate a structured, typed object for a given prompt and schema using a language model.
@@ -288,6 +289,19 @@ Logprobs for the completion.
     this.rawResponse = options.rawResponse;
     this.logprobs = options.logprobs;
   }
+
+  /**
+Converts the object to a JSON response.
+The response will have a status code of 200 and a content type of `application/json; charset=utf-8`.
+   */
+  toJsonResponse(init?: ResponseInit): Response {
+    return new Response(JSON.stringify(this.object), {
+      status: init?.status ?? 200,
+      headers: prepareResponseHeaders(init, {
+        contentType: 'application/json; charset=utf-8',
+      }),
+    });
+  }
 }
 
 /**

packages/core/core/generate-object/stream-object.ts

@@ -580,6 +580,7 @@ writes each text delta as a separate chunk.
 
   /**
 Creates a simple text stream response.
+The response has a `Content-Type` header set to `text/plain; charset=utf-8`.
 Each text delta is encoded as UTF-8 and sent as a separate chunk.
 Non-text-delta events are ignored.