fastapi: openapi.json fails to be generated for nested models

Describe the bug Fails to autogenerate docs.

To Reproduce

Create a response model with other nested models and try to generate openapi.json or open autogenerated docs.
Application throws an error

Expected behavior Generate openapi.json and open autogenerated docs without problems.

Environment:

OS: macOS
FastAPI Version: 0.30.0
Python version: 3.7.3

Additional context

My models look like this:

class PaginatedItems(Generic[Item], BaseModel, abc.ABC):
    items: List[Any]
    has_after: bool = False
    has_before: bool = False

class OrderUser(BaseModel):
    name: Optional[str] = None
    email: EmailStr


class Order(BaseModel):
    order_id: UUID
    amount: Decimal
    currency: str

    # Users part
    merchants: List[OrderUser]
    handlers: List[OrderUser]

class PaginatedOrders(PaginatedItems[Order]):
    items: List[Order] = list()

My route definition looks like that:

@router.get(orders_uri,
            response_model=PaginatedOrders
async def list():
	...

This results in the following exception when trying to open autogenerated docs:

pydantic.error_wrappers.ValidationError: 4 validation errors
schemas -> OrderUser
  value is not a valid dict (type=type_error.dict)
schemas -> OrderUser
  value is not a valid dict (type=type_error.dict)
components -> schemas
  value is not none (type=type_error.none.allowed)
components
  value is not none (type=type_error.none.allowed)

When I comment out the response_model=PaginatedOrders part from route definition everything works, but docs obviously miss response type.

About this issue

Original URL
State: closed
Created 5 years ago
Comments: 15 (4 by maintainers)

Commits related to this issue

Fixed pydantic issue on API docs Bug seems to be fixed in fastapi version 0.33: https://github.com/tiangolo/fastapi/issues/383 — committed to bcgov-c/wally by dainetrinidad 4 years ago

Most upvoted comments

oups sorry I think your mistake is putting response_model=SimilarProducts, in the wrong spot, it’s in the @router part

+12

euri10 on Jul 23, 2019

I can confirm it now works fine! Thanks for fixing it so quickly!

LKay on Jul 15, 2019

@tiangolo yes, I’m happy to say I’ve removed the above workaround from my projects. Thanks!

dmontagu on Jul 14, 2019

@yeus I happened to stumble upon it by accident and reposted 👍

Nicholas-Schaub on Aug 28, 2021

I have similar code structure to @yeus and also am running into this issue. I only have issues with response_model values that have nested iterable types (i.e. List, Tuple, Dict). I did some additional testing that made me think this was a Windows vs Linux issue, but upon further investigation I found that something became broken in the most recent version of fastapi.

This code will generate proper documentation when using fastapi[standard]==0.65.2 but does not generate proper documentation in fastapi[standard]==0.68.1.

# Obviously skipping some imports

class DataResponse(BaseModel):
    data: typing.List[int]
    limits: typing.List[typing.Tuple[float,float]]
    counts: typing.Tuple[int,int]

@app.post("/bins",
          status_code=status.HTTP_200_OK,
          tags=["data"],
          response_model=DataResponse)
def bins(input: DataSelection):

    return None

if __name__ == "__main__":
    import uvicorn

    uvicorn.run("server:app", host="127.0.0.1", port=8001, log_level="info")

When the above is run using fastapi[standard]==0.65.2, I can access documentation at 127.0.0.1:8001/docs.

When the above is run using fastapi[standard]==0.68.1, I receive the following error:

  File "pydantic\main.py", line 406, in pydantic.main.BaseModel.__init__
pydantic.error_wrappers.ValidationError: 3 validation errors for OpenAPI
components -> schemas -> DataResponse -> properties -> limits -> items -> items
  value is not a valid dict (type=type_error.dict)
components -> schemas -> DataResponse -> properties -> counts -> items
  value is not a valid dict (type=type_error.dict)
components -> schemas -> DataResponse -> $ref
  field required (type=value_error.missing)

For now, I am just downgrading fastapi so that documentation works.

Nicholas-Schaub on Aug 28, 2021

I feel like reopening this bug. I get the same erros as above by using a nested model like this:

Dict[str, List[Tuple[str, float]]]

I am on: fastapi version: ‘0.68.1’, python 3.8.10, ubuntu 20.04.

this code here:

from typing import List, Dict, Tuple

from fastapi import FastAPI
from pydantic import BaseModel

app = FastAPI()

class Answers(BaseModel):
    answers: Dict[str, List[Tuple[str, float]]] = {}

@app.get("/qa", response_model=Answers)
async def qatask(request: str):
    return Answers()

if __name__ == "__main__":
    import uvicorn
    uvicorn.run("bugfind:app", host="0.0.0.0", port=5000, reload=True,
                workers=1)  # , debug=True)

causes the same error to appear.

Traceback (most recent call last):
  File "//home/name/.local/lib/python3.8/site-packages/uvicorn/protocols/http/h11_impl.py", line 373, in run_asgi
    result = await app(self.scope, self.receive, self.send)
  File "//home/name/.local/lib/python3.8/site-packages/uvicorn/middleware/proxy_headers.py", line 75, in __call__
    return await self.app(scope, receive, send)
  File "//home/name/.local/lib/python3.8/site-packages/fastapi/applications.py", line 208, in __call__
    await super().__call__(scope, receive, send)
  File "//home/name/.local/lib/python3.8/site-packages/starlette/applications.py", line 112, in __call__
    await self.middleware_stack(scope, receive, send)
  File "//home/name/.local/lib/python3.8/site-packages/starlette/middleware/errors.py", line 181, in __call__
    raise exc from None
  File "//home/name/.local/lib/python3.8/site-packages/starlette/middleware/errors.py", line 159, in __call__
    await self.app(scope, receive, _send)
  File "//home/name/.local/lib/python3.8/site-packages/starlette/exceptions.py", line 82, in __call__
    raise exc from None
  File "//home/name/.local/lib/python3.8/site-packages/starlette/exceptions.py", line 71, in __call__
    await self.app(scope, receive, sender)
  File "//home/name/.local/lib/python3.8/site-packages/starlette/routing.py", line 580, in __call__
    await route.handle(scope, receive, send)
  File "//home/name/.local/lib/python3.8/site-packages/starlette/routing.py", line 241, in handle
    await self.app(scope, receive, send)
  File "//home/name/.local/lib/python3.8/site-packages/starlette/routing.py", line 52, in app
    response = await func(request)
  File "//home/name/.local/lib/python3.8/site-packages/fastapi/applications.py", line 161, in openapi
    return JSONResponse(self.openapi())
  File "//home/name/.local/lib/python3.8/site-packages/fastapi/applications.py", line 136, in openapi
    self.openapi_schema = get_openapi(
  File "//home/name/.local/lib/python3.8/site-packages/fastapi/openapi/utils.py", line 410, in get_openapi
    return jsonable_encoder(OpenAPI(**output), by_alias=True, exclude_none=True)  # type: ignore
  File "pydantic/main.py", line 406, in pydantic.main.BaseModel.__init__
pydantic.error_wrappers.ValidationError: 4 validation errors for OpenAPI
components -> schemas -> Answers -> properties -> answers -> additionalProperties -> items -> items
  value is not a valid dict (type=type_error.dict)
components -> schemas -> Answers -> properties -> answers -> additionalProperties -> $ref
  field required (type=value_error.missing)
components -> schemas -> Answers -> properties -> answers -> additionalProperties
  value could not be parsed to a boolean (type=type_error.bool)
components -> schemas -> Answers -> $ref
  field required (type=value_error.missing)

yeus on Aug 28, 2021