"Event": {
                        "title": "Event",
                        "required": ["name", "total"],
                        "type": "object",
                        "properties": {
                            "name": {"title": "Name", "type": "string"},
                            "total": {"title": "Total", "type": "number"},
                        },
                    },
                    "HTTPValidationError": {

                            "anyOf": [{"type": "string"}, {"type": "null"}],
                        },
                        "customer": {"title": "Customer", "type": "string"},
                        "total": {"title": "Total", "type": "number"},
                    },
                },
                "InvoiceEvent": {
                    "title": "InvoiceEvent",
                    "required": ["description", "paid"],

        }
    }

    /**
     * Returns the total number of documents processed.
     *
     * @return the number of documents processed
     */
    @Override
    public long getDocumentSize() {
        return documentSize.get();
    }

    /**
     * Returns the total execution time for all operations.
     *
     * @return the total execution time in milliseconds
     */
    @Override

* `datetime.timedelta`:
    * Un `datetime.timedelta` de Python.
    * En requests y responses se representará como un `float` de segundos totales.

    protected IndexingHelper indexingHelper;

    /** Flag indicating if crawling should be finished */
    protected boolean finishCrawling = false;

    /** Total execution time in milliseconds */
    protected long executeTime;

    /** Total number of processed documents */
    protected long documentSize;

    /** Maximum number of indexer errors allowed */
    protected int maxIndexerErrorCount = 0;

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

app = FastAPI()


class Invoice(BaseModel):
    id: str
    title: str | None = 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(

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

app = FastAPI()


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


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


class InvoiceEventReceived(BaseModel):
    ok: bool


invoices_callback_router = APIRouter()

Давайте рассмотрим это на примере.

Представьте, что вы разрабатываете приложение, позволяющее создавать счета.

Эти счета будут иметь `id`, `title` (необязательный), `customer` и `total`.

Пользователь вашего API (внешний разработчик) создаст счет в вашем API с помощью POST-запроса.

Затем ваш API (предположим) сделает следующее:

* Отправит счет клиенту внешнего разработчика.
* Получит оплату.

Stellen Sie sich vor, Sie entwickeln eine Anwendung, mit der Sie Rechnungen erstellen können.

Diese Rechnungen haben eine `id`, einen optionalen `title`, einen `customer` (Kunde) und ein `total` (Gesamtsumme).

Der Benutzer Ihrer API (ein externer Entwickler) erstellt mit einem POST-Request eine Rechnung in Ihrer API.

Dann wird Ihre API (stellen wir uns vor):

## An app with callbacks { #an-app-with-callbacks }

Let's see all this with an example.

Imagine you develop an app that allows creating invoices.

These invoices will have an `id`, `title` (optional), `customer`, and `total`.

The user of your API (an external developer) will create an invoice in your API with a POST request.

Then your API will (let's imagine):

* Send the invoice to some customer of the external developer.