author_link: https://medium.com/@krishnardt365
    link: https://medium.com/@krishnardt365/fastapi-docker-and-postgres-91943e71be92
    title: Fastapi, Docker(Docker compose) and Postgres
  German:
  - author: Marcel Sander (actidoo)
    author_link: https://www.actidoo.com
    link: https://www.actidoo.com/de/blog/python-fastapi-domain-driven-design
    title: Domain-driven Design mit Python und FastAPI
  - author: Nico Axtmann

* Fournir directement 2 interfaces web de documentation interactive.

---

Nous n'avons fait qu'effleurer la surface, mais vous avez déjà une idée de la façon dont tout cela fonctionne.

Essayez de changer la ligne contenant :

```Python
    return {"item_name": item.name, "item_id": item_id}
```

... de :

```Python
        ... "item_name": item.name ...
```

... vers :

When a request contains invalid data, **FastAPI** internally raises a `RequestValidationError`.

And it also includes a default exception handler for it.

To override it, import the `RequestValidationError` and use it with `@app.exception_handler(RequestValidationError)` to decorate the exception handler.

The exception handler will receive a `Request` and the exception.

```Python hl_lines="2  14-16"
{!../../../docs_src/handling_errors/tutorial004.py!}

    )


async def request_validation_exception_handler(
    request: Request, exc: RequestValidationError
) -> JSONResponse:
    return JSONResponse(
        status_code=HTTP_422_UNPROCESSABLE_ENTITY,
        content={"detail": jsonable_encoder(exc.errors())},
    )


async def websocket_request_validation_exception_handler(
    websocket: WebSocket, exc: WebSocketRequestValidationError
) -> None:

participant client as Client
participant handler as Exception handler
participant dep as Dep with yield
participant operation as Path Operation
participant tasks as Background tasks

    Note over client,operation: Can raise exceptions, including HTTPException
    client ->> dep: Start request
    Note over dep: Run code up to yield
    opt raise Exception
        dep -->> handler: Raise Exception

```Python hl_lines="8"
{!../../../docs_src/events/tutorial001.py!}
```

In this case, the `startup` event handler function will initialize the items "database" (just a `dict`) with some values.

You can add more than one event handler function.

And your application won't start receiving requests until all the `startup` event handlers have completed.

### `shutdown` event

class GzipRoute(APIRoute):
    def get_route_handler(self) -> Callable:
        original_route_handler = super().get_route_handler()

        async def custom_route_handler(request: Request) -> Response:
            request = GzipRequest(request.scope, request.receive)
            return await original_route_handler(request)

        return custom_route_handler


app = FastAPI()
app.router.route_class = GzipRoute

    opt raise
        dep -->> handler: Raise HTTPException
        handler -->> client: HTTP error response
        dep -->> dep: Raise other exception
    end
    dep ->> operation: Run dependency, e.g. DB session
    opt raise
        operation -->> dep: Raise HTTPException
        dep -->> handler: Auto forward exception
        handler -->> client: HTTP error response

    opt raise
        dep -->> handler: Raise HTTPException
        handler -->> client: HTTP error response
        dep -->> dep: Raise other exception
    end
    dep ->> operation: Run dependency, e.g. DB session
    opt raise
        operation -->> dep: Raise HTTPException
        dep -->> handler: Auto forward exception
        handler -->> client: HTTP error response

    @classmethod
    def __get_pydantic_json_schema__(
        cls, core_schema: CoreSchema, handler: GetJsonSchemaHandler
    ) -> JsonSchemaValue:
        return {"type": "string", "format": "binary"}

    @classmethod
    def __get_pydantic_core_schema__(
        cls, source: Type[Any], handler: Callable[[Any], CoreSchema]
    ) -> CoreSchema:
        return with_info_plain_validator_function(cls._validate)