Node

Record Final Object after Streaming Object

Learn how to record the final object after streaming an object using the AI SDK and Node

When you're streaming structured data, you may want to record the final object for logging or other purposes.

`onEnd` and `output`

Use onEnd for metadata like token usage and await result.output for the final structured object.

index.ts

import { streamText, Output } from 'ai';
import { z } from 'zod';

const result = streamText({
  model: 'openai/gpt-6-astra',
  output: Output.object({
    schema: z.object({
      recipe: z.object({
        name: z.string(),
        ingredients: z.array(z.string()),
        steps: z.array(z.string()),
      }),
    }),
  }),
  prompt: 'Generate a lasagna recipe.',
  onEnd({ usage }) {
    console.log('Token usage:', usage);
  },
});

for await (const _ of result.partialOutputStream) {
}

try {
  const output = await result.output;
  console.log('Final object:', JSON.stringify(output, null, 2));
} catch (error) {
  console.error('Failed to parse output:', error);
}

The streamText result contains an output promise that resolves to the final object. The object is fully typed. When the type validation according to the schema fails, the promise will be rejected with a TypeValidationError.

index.ts

import { streamText, Output } from 'ai';
import { z } from 'zod';

const result = streamText({
  model: 'openai/gpt-6-astra',
  output: Output.object({
    schema: z.object({
      recipe: z.object({
        name: z.string(),
        ingredients: z.array(z.string()),
        steps: z.array(z.string()),
      }),
    }),
  }),
  prompt: 'Generate a lasagna recipe.',
});

for await (const partialObject of result.partialOutputStream) {
}

try {
  const { recipe } = await result.output;
  console.log('Recipe:', JSON.stringify(recipe, null, 2));
} catch (error) {
  console.error(error);
}

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