[BUG] Swagger KeyError when two classes contain inner classes with the same name

Describe the bug

KeyError when two classes contain inner classes with the same name. If i rename one of the inner classes, app runs good.

To Reproduce

Steps to reproduce the behavior with a minimum self-contained file.

Replace each part with your own scenario:

1. Create a file with:

from __future__ import annotations

from typing import Union

import uvicorn
from fastapi import FastAPI
from pydantic import BaseModel


class X(BaseModel):
    class A(BaseModel):
        pass

    a: X.A


X.update_forward_refs()


class Y(BaseModel):
    class A(BaseModel):
        pass

    y: Y.A


Y.update_forward_refs()

app = FastAPI()


@app.get("/")
def route(request: Union[X, Y]):
    return str(request)

1. Open the browser and call the endpoint /docs.
2. It show Fetch error Internal Server Error /openapi.json and the app raise an error

  File "/usr/local/lib/python3.7/site-packages/fastapi/utils.py", line 64, in get_model_definitions
    model_name = model_name_map[model]
KeyError: <class '__main__.X.A'>

Environment

• OS: MacOS
• FastAPI Version : 0.55.1
• Python: 3.8.2

[mike0sv]

I generate endpoints dynamically based on some config, and generate models for those endpoints with pydantic.create_model. Code in get_model_name_map silently drops models with identical names, which leads to uninformative KeyError later.

[guissart]

@sureshjoshi @tanyaofei reading this issue saved my day.

I had a duplicated Enum class with the same name across two Pydantic model. And the Key error that it produced doesn’t give many clue on what happened.

Naming differently the two Enum class solve the problem.