multiple callbacks

[arabnejad]

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Example Code

from typing import Optional
import uvicorn
from fastapi import APIRouter, FastAPI
from pydantic import BaseModel

app = FastAPI()

class Invoice(BaseModel):
    id: str
    title: Optional[str] = None
    customer: str
    total: float


class InvoiceEvent(BaseModel):
    description: str
    paid: bool


class InvoiceEventReceived(BaseModel):
    ok: bool

class InvoiceEventReceived2(BaseModel):
    okydoky: bool

invoices_callback_router = APIRouter()
@invoices_callback_router.post(
    "{$callback_url}/invoices/{$request.body.id}", response_model=InvoiceEventReceived
)
def invoice_notification(body: InvoiceEvent):
    pass

invoices_callback_router2 = APIRouter()
@invoices_callback_router2.post(
    "{$callback_url2}/invoices2/{$request.body.id}", response_model=InvoiceEventReceived2
)
def invoice_notification2(body: InvoiceEvent):
    pass



@app.post("/invoices/", callbacks=[invoices_callback_router.routes, invoices_callback_router2.routes])
def create_invoice(invoice: Invoice):
    return {"msg": "Invoice received"}


if __name__ == "__main__":
    uvicorn.run(app, host="0.0.0.0", port=8000)

Description

Hi

I am trying to have multiple callbacks for a post endpoint,
based on the source code (https://github.com/tiangolo/fastapi/blob/master/fastapi/applications.py#L558), the callbacks arg should accept a list, however, when I passed multiple callbacks as a list, in the generated openapi.json, I have

        "callbacks": {}

did I do something wrong or should I used another approach for this purpose

my goal is to have something like this in documentation

Operating System

Linux

Operating System Details

No response

FastAPI Version

0.75.1

Python Version

3.8.10

Additional Context

No response

[arabnejad]

I just add some logging line in https://github.com/tiangolo/fastapi/blob/master/fastapi/applications.py#L563

    ) -> Callable[[DecoratedCallable], DecoratedCallable]:
        print(f"len(callbacks) = {len(callbacks)}")
        for callback in callbacks:
            print(type(callback))
            if isinstance(callback, list):
                print(type(callback[0]))

if I use

@app.post("/invoices/", callbacks=invoices_callback_router.routes)

then, the output will be

len(callbacks) = 1
<class 'fastapi.routing.APIRoute'>

however, by setting

@app.post("/invoices/", callbacks=[invoices_callback_router.routes, invoices_callback_router2.routes])

we will have

len(callbacks) = 2
<class 'list'>
<class 'fastapi.routing.APIRoute'>
<class 'list'>
<class 'fastapi.routing.APIRoute'>

so, as you can see, in the second case, it seems we have array of arrays !

[arabnejad]

I could fix it within

class FastAPI(Starlette):
    ...
    ...
    ...
    def post(
                 ...
                 ...
    ) -> Callable[[DecoratedCallable], DecoratedCallable]:
        tmp_callbacks = []
        for callback in callbacks:
            if isinstance(callback, list):
                tmp_callbacks.append(callback[0])
            else:
                tmp_callbacks.append(callback)

        return self.router.post(
            ...
            callbacks=tmp_callbacks,
            ...

I am not sure, but in my point of view, it seems this is a bug

[arabnejad]

we can also use to resolve the issue

@app.post("/invoices/", callbacks=invoices_callback_router.routes + invoices_callback_router2.routes)

APIRouter().routes returns a list object, so, I think this should be the better approach