First Check

• I added a very descriptive title here.
• I used the GitHub search to find a similar question and didn't find it.
• I searched the FastAPI documentation, with the integrated search.
• I already searched in Google "How to X in FastAPI" and didn't find any information.
• I already read and followed all the tutorial in the docs and didn't find an answer.
• I already checked if it is not related to FastAPI but to Pydantic.
• I already checked if it is not related to FastAPI but to Swagger UI.
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Commit to Help

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Example Code

from typing import Optional

from fastapi import FastAPI
from pydantic import BaseModel

app = FastAPI()


class Message(BaseModel):
    message: str
    # commenting this will work
    details: Optional[list["Message"]] = None


@app.get("/hello", response_model=Message)
def hello() -> Message:
    return Message(message="Hello World")


# source .venv/bin/activate
# uvicorn main.py --port 8020

Description

The shared code snippet has one API route (/hello) that returns Message object. The Message schema has recursive association to itself - Message has details which is a list Message(s).

• In the swagger UI (http://127.0.0.1:8020/docs) when I expand the endpoint /hello it gets stuck in loading, and soon after the whole page becomes unresponsive.
• If I comment the details field in Message, it works
• I did some digging and I found that swagger-ui-dist 5.9.1 released recently is causing this issue, this was ok in previous version 5.9.0.

I expected this to work like before for all released version of swagger-ui-dist

I have 3 questions:

1. Is there something I have missed, that could help me define the message schema correctly so that swagger doesn't have issues with it?
2. Or is there some tweaking required in the generated openapi json?
3. I have used the code snippet given in OpenAPI UI not working properly when using automatic swagger-ui CDN (swagger-ui-3.30.1) #1762 (comment) to monkey patch swagger_js_url to https://cdn.jsdelivr.net/npm/swagger-ui-dist@5.9.0/swagger-ui-bundle.js. This works for now. But is there any other way to specify the swagger-ui version to be used?

Operating System

macOS

Operating System Details

No response

FastAPI Version

0.104.0

Pydantic Version

2.4.2

Python Version

3.11.4

Additional Context

I have also added a comment here swagger-api/swagger-ui#9337 (comment) regarding the same.