[BUG][typescript-fetch][NodeJS] Requests hang if response body is larger than 16kb

[eyalroth]

Bug Report Checklist

• Have you provided a full/minimal spec to reproduce the issue?
• Have you validated the input using an OpenAPI validator (example)?
• Have you tested with the latest master to confirm the issue still exists?
• Have you searched for related issues/PRs?
• What's the actual output vs expected output?
• [Optional] Sponsorship to speed up the bug fix or feature request (example)

Description

In clients generated with typescript-fetch and used in NodeJS, if a post-middleware is added to client (withPostMiddleware) and tries to read the body of the response, then the request will hang when the body is larger than 16kb.

The culprit is the invocation of Response.clone(). Similarly to ReadableStream.tee() (which I suspect clone is invoking under the hood), the usage of this method is intended to be used for parallel consumption of the stream; however, the generated code consumes it sequentially.

When using this method, both the consumer of the original response (the main API method) and the consumer of the clone (the middleware) have to continuously read the body stream. If one of them does not read it, the underlying stream of both of them will stop reading data from the source once it reaches the highWaterMark of the stream, which is essentially the max size of the stream's buffer. In NodeJS, the default value of highWaterMark is 16kb.

openapi-generator version

Latest (7.5.0), not a regression.

OpenAPI declaration file content or url

This applies to any response that contains a body.

Steps to reproduce

let api = new MyGeneratedApi();

api = api.withPostMiddleware(async (context: ResponseContext) => { console.log(await context?.response?.text()) });

// hangs if body is larger than 16kb
const data = await api.getData();

Suggest a fix

Instead of cloning the response (here and here), the generated code should:

1. Fully read the body before invoking the post middlewares.
2. Pass the body it to the middle-wares as is (as a partial Response object).
3. Construct a new (node-fetch) Response, so that the main API call can consume the body normally (once we read the body in step 1, the original response can no longer be used).

[wing328]

your suggestion sounds good. may I know if you've time to contribute a PR for that enhancement?