# Record Final Object after Streaming Object

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

## `onFinish` Callback

You can use the `onFinish` callback to record the final object.
It is called when the stream is finished.

The `object` parameter contains the final object, or `undefined` if the type validation fails.
There is also an `error` parameter that contains error when e.g. the object does not match the schema.

```ts file='index.ts' highlight={"15-23"}
import { streamObject } from 'ai';
import { z } from 'zod';

const result = streamObject({
  model: 'openai/gpt-4.1',
  schema: z.object({
    recipe: z.object({
      name: z.string(),
      ingredients: z.array(z.string()),
      steps: z.array(z.string()),
    }),
  }),
  prompt: 'Generate a lasagna recipe.',
  onFinish({ object, error }) {
    // handle type validation failure (when the object does not match the schema):
    if (object === undefined) {
      console.error('Error:', error);
      return;
    }

    console.log('Final object:', JSON.stringify(object, null, 2));
  },
});
```

## `object` Promise

The [`streamObject`](/docs/reference/ai-sdk-core/stream-object) result contains an `object` 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`.

```ts file='index.ts' highlight={"17-26"}
import { streamObject } from 'ai';
import { z } from 'zod';

const result = streamObject({
  model: 'openai/gpt-4.1',
  schema: z.object({
    recipe: z.object({
      name: z.string(),
      ingredients: z.array(z.string()),
      steps: z.array(z.string()),
    }),
  }),
  prompt: 'Generate a lasagna recipe.',
});

result.object
  .then(({ recipe }) => {
    // do something with the fully typed, final object:
    console.log('Recipe:', JSON.stringify(recipe, null, 2));
  })
  .catch(error => {
    // handle type validation failure
    // (when the object does not match the schema):
    console.error(error);
  });

// note: the stream needs to be consumed because of backpressure
for await (const partialObject of result.partialObjectStream) {
}
```


## Navigation

- [Generate Text](/v5/cookbook/node/generate-text)
- [Retrieval Augmented Generation](/v5/cookbook/node/retrieval-augmented-generation)
- [Knowledge Base Agent](/v5/cookbook/node/knowledge-base-agent)
- [Generate Text with Chat Prompt](/v5/cookbook/node/generate-text-with-chat-prompt)
- [Generate Text with Image Prompt](/v5/cookbook/node/generate-text-with-image-prompt)
- [Stream Text](/v5/cookbook/node/stream-text)
- [Stream Text with Chat Prompt](/v5/cookbook/node/stream-text-with-chat-prompt)
- [Stream Text with Image Prompt](/v5/cookbook/node/stream-text-with-image-prompt)
- [Stream Text with File Prompt](/v5/cookbook/node/stream-text-with-file-prompt)
- [Generate Object with a Reasoning Model](/v5/cookbook/node/generate-object-reasoning)
- [Generate Object](/v5/cookbook/node/generate-object)
- [Stream Object](/v5/cookbook/node/stream-object)
- [Stream Object with Image Prompt](/v5/cookbook/node/stream-object-with-image-prompt)
- [Record Token Usage After Streaming Object](/v5/cookbook/node/stream-object-record-token-usage)
- [Record Final Object after Streaming Object](/v5/cookbook/node/stream-object-record-final-object)
- [Call Tools](/v5/cookbook/node/call-tools)
- [Call Tools with Image Prompt](/v5/cookbook/node/call-tools-with-image-prompt)
- [Call Tools in Multiple Steps](/v5/cookbook/node/call-tools-multiple-steps)
- [Model Context Protocol (MCP) Tools](/v5/cookbook/node/mcp-tools)
- [Manual Agent Loop](/v5/cookbook/node/manual-agent-loop)
- [Web Search Agent](/v5/cookbook/node/web-search-agent)
- [Model Context Protocol (MCP) Elicitation](/v5/cookbook/node/mcp-elicitation)
- [Embed Text](/v5/cookbook/node/embed-text)
- [Embed Text in Batch](/v5/cookbook/node/embed-text-batch)
- [Intercepting Fetch Requests](/v5/cookbook/node/intercept-fetch-requests)
- [Local Caching Middleware](/v5/cookbook/node/local-caching-middleware)


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