How to dynamically send json body in callback request

Hello,

I am following to fastAPI callbacks here : https://fastapi.tiangolo.com/advanced/openapi-callbacks/ to try to set up slack alerts in one of my projects.

My goal is to sending a slack message whenever the API request failed. My code looks like this:

from typing import Optional

from fastapi import APIRouter, FastAPI
from pydantic import BaseModel, HttpUrl

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


invoices_callback_router = APIRouter()


@invoices_callback_router.post("", response_model=InvoiceEventReceived)
def invoice_notification(body: InvoiceEvent):
    return {"okay": "yes"}


@app.post("/invoices/", callbacks=invoices_callback_router.routes)
def create_invoice(invoice: Invoice, callback_url: Optional[HttpUrl] = None):
    return {"msg": "Invoice received"}

I would input slack webhooks link in callback_url, however, I am not very sure where to put payload for the callback_url, anyone could help ?

[AmeyMore98]

OpenAPI Callbacks is only used to let your users know, how an external callback API should look like. For making the actual callback request, you will have to use something like HTTPX or Requests. A sample code for sending callback:

callback_url = "https://example.com/api/v1/callback"
callback_payload= {"detail": "Request processed"}
requests.post(callback_url, json=callback_payload)

Now coming to your use case of Slack alerts, I don’t think you event need to use OpenAPI Callbacks. You could just catch any errors using try/except, parse the errors, and send the alert using slackclient. For multiple endpoints you could also use decorators to reduce code duplication.

Hope this helps! 😃

[github-actions[bot]]

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