StreamingTextResponse

StreamingTextResponse(res: ReadableStream, init?: ResponseInit): Response

StreamingTextResponse is a utility class that simplifies the process of returning a ReadableStream of text in HTTP responses. It is a lightweight wrapper around the native Response class, automatically setting the status code to 200 and the Content-Type header to 'text/plain; charset=utf-8'.

Parameters

res: ReadableStream

This parameter should be a ReadableStream which represents the content of the HTTP response.

init?: ResponseInit

This optional parameter can be used to customize the properties of the HTTP response. It is an object that corresponds to the ResponseInit object used in the Response constructor.

The ResponseInit object can contain the following properties:

• status?: number: The status code for the response. StreamingTextResponse will overwrite this value with 200.
• statusText?: string: The status message associated with the status code.
• headers?: HeadersInit: Any headers you want to add to your response. StreamingTextResponse will add 'Content-Type': 'text/plain; charset=utf-8' to these headers.

Returns

StreamingTextResponse returns an instance of Response with the provided ReadableStream as the body, the status set to 200, and the Content-Type header set to 'text/plain; charset=utf-8'. Additional headers and properties can be added using the init parameter.

Example

import OpenAI from 'openai';
import { OpenAIStream, StreamingTextResponse } from 'ai';
 
// Create an OpenAI API client (that's edge friendly!)
const openai = new OpenAI({
  apiKey: process.env.OPENAI_API_KEY || '',
});
 
// IMPORTANT! Set the runtime to edge
export const runtime = 'edge';
 
export async function POST() {
  const response = await openai.chat.completions.create({
    model: 'gpt-4',
    stream: true,
    messages: [{ role: 'user', content: 'What is love?' }],
  });
  const stream = OpenAIStream(response);
  return new StreamingTextResponse(stream, {
    headers: { 'X-RATE-LIMIT': 'lol' },
  });
  // Returns a Response with the stream as the body,
  // status code 200,
  // and headers 'Content-Type': 'text/plain; charset=utf-8' and 'X-RATE-LIMIT': 'lol'.
}

In this example, StreamingTextResponse is used to return a stream of text from the OpenAI chat completion endpoint as an HTTP response with additional custom headers.