Nest.js

You can use the AI SDK in a Nest.js server to generate and stream text and objects to the client.

Examples

The examples show how to implement a Nest.js controller that uses the AI SDK to stream text and objects to the client.

Full example: github.com/vercel/ai/examples/nest

Data Stream

You can use the pipeDataStreamToResponse method to get a data stream from the result and then pipe it to the response.

app.controller.ts
import { Controller, Post, Res } from '@nestjs/common';
import { openai } from '@ai-sdk/openai';
import { streamText } from 'ai';
import { Response } from 'express';
@Controller()
export class AppController {
@Post()
async example(@Res() res: Response) {
const result = streamText({
model: openai('gpt-4o'),
prompt: 'Invent a new holiday and describe its traditions.',
});
result.pipeDataStreamToResponse(res);
}
}

Sending Custom Data

createDataStream can be used to send custom data to the client.

app.controller.ts
import { Controller, Post, Res } from '@nestjs/common';
import { openai } from '@ai-sdk/openai';
import { createDataStream, streamText } from 'ai';
import { Response } from 'express';
@Controller()
export class AppController {
@Post('/stream-data')
async streamData(@Res() res: Response) {
pipeDataStreamToResponse(res, {
execute: async dataStreamWriter => {
dataStreamWriter.writeData('initialized call');
const result = streamText({
model: openai('gpt-4o'),
prompt: 'Invent a new holiday and describe its traditions.',
});
result.mergeIntoDataStream(dataStreamWriter);
},
onError: error => {
// Error messages are masked by default for security reasons.
// If you want to expose the error message to the client, you can do so here:
return error instanceof Error ? error.message : String(error);
},
});
}
}

Text Stream

You can use the pipeTextStreamToResponse method to get a text stream from the result and then pipe it to the response.

app.controller.ts
import { Controller, Post, Res } from '@nestjs/common';
import { openai } from '@ai-sdk/openai';
import { streamText } from 'ai';
import { Response } from 'express';
@Controller()
export class AppController {
@Post()
async example(@Res() res: Response) {
const result = streamText({
model: openai('gpt-4o'),
prompt: 'Invent a new holiday and describe its traditions.',
});
result.pipeTextStreamToResponse(res);
}
}