BasicsGenerating Structured Data

Generate Object

Earlier functions like generateText and streamText gave us the ability to generate unstructured text. However, if you want to generate structured data like JSON, you can provide a schema that describes the structure of your desired object to the generateObject function.

The function requires you to provide a schema using zod, a library for defining schemas for JavaScript objects. By using zod, you can also use it to validate the generated object and ensure that it conforms to the specified structure.

http://localhost:3000

View Notifications

Client

Let's create a simple React component that will make a POST request to the /api/completion endpoint when a button is clicked. The endpoint will return the generated object based on the input prompt and we'll display it.

pages/index.tsx

import { useState } from 'react';

export default function Page() {
  const [generation, setGeneration] = useState();
  const [isLoading, setIsLoading] = useState(false);

  return (
    <div>
      <div
        onClick={async () => {
          setIsLoading(true);

          await fetch('/api/completion', {
            method: 'POST',
            body: JSON.stringify({
              prompt: 'Messages during finals week.',
            }),
          }).then(response => {
            response.json().then(json => {
              setGeneration(json.object);
              setIsLoading(false);
            });
          });
        }}
      >
        Generate
      </div>

      {isLoading ? 'Loading...' : <pre>{JSON.stringify(generation)}</pre>}
    </div>
  );
}

Server

Let's create a route handler for /api/completion that will generate an object based on the input prompt. The route will call the generateObject function from the ai module, which will then generate an object based on the input prompt and return it.

app/api/completion/route.ts

import { generateObject } from 'ai';
import { openai } from '@ai-sdk/openai';
import { z } from 'zod';

export async function POST(req: Request) {
  const { prompt }: { prompt: string } = await req.json();

  const result = await generateObject({
    model: openai('gpt-4'),
    system: 'You generate three notifications for a messages app.',
    prompt,
    schema: z.object({
      notifications: z.array(
        z.object({
          name: z.string().describe('Name of a fictional person.'),
          message: z.string().describe('Do not use emojis or links.'),
          minutesAgo: z.number(),
        }),
      ),
    }),
  });

  return result.toJsonResponse();
}

View Example on GitHub