app = FastAPI()


@app.exception_handler(StarletteHTTPException)
async def http_exception_handler(request, exc):
    return PlainTextResponse(str(exc.detail), status_code=exc.status_code)


@app.exception_handler(RequestValidationError)
async def validation_exception_handler(request, exc: RequestValidationError):
    message = "Validation errors:"
    for error in exc.errors():

app = FastAPI()


@app.exception_handler(StarletteHTTPException)
async def custom_http_exception_handler(request, exc):
    print(f"OMG! An HTTP error!: {repr(exc)}")
    return await http_exception_handler(request, exc)


@app.exception_handler(RequestValidationError)
async def validation_exception_handler(request, exc):
    print(f"OMG! The client sent invalid data!: {exc}")

## Utiliser `async` ou non { #to-async-or-not-to-async }

Comme les dépendances seront aussi appelées par **FastAPI** (tout comme vos fonctions de chemins d’accès), les mêmes règles s’appliquent lors de la définition de vos fonctions.

Vous pouvez utiliser `async def` ou un `def` normal.

        {"detail": exc.detail}, status_code=exc.status_code, headers=headers
    )


async def request_validation_exception_handler(
    request: Request, exc: RequestValidationError
) -> JSONResponse:
    return JSONResponse(
        status_code=422,
        content={"detail": jsonable_encoder(exc.errors())},
    )


async def websocket_request_validation_exception_handler(

from fastapi.responses import HTMLResponse

app = FastAPI()


@app.post("/files/")
async def create_files(
    files: list[bytes] = File(description="Multiple files as bytes"),
):
    return {"file_sizes": [len(file) for file in files]}


@app.post("/uploadfiles/")
async def create_upload_files(
    files: list[UploadFile] = File(description="Multiple files as UploadFile"),
):

from fastapi import FastAPI, Security
from fastapi.security import SecurityScopes
from fastapi.testclient import TestClient


async def security1(scopes: SecurityScopes):
    return scopes.scopes


async def security2(scopes: SecurityScopes):
    return scopes.scopes


async def dep3(
    dep1: Annotated[list[str], Security(security1, scopes=["scope1"])],

    * Bu, özellikle bir kez `await myfile.read()` çalıştırdıysanız ve sonra içeriği yeniden okumaya ihtiyaç duyuyorsanız faydalıdır.
* `close()`: Dosyayı kapatır.

Bu method’ların hepsi `async` olduğundan, bunları "await" etmeniz gerekir.

Örneğin, bir `async` *path operation function* içinde içeriği şöyle alabilirsiniz:

```Python
contents = await myfile.read()
```

):
    return [item, sub_item]


@app.post("/with-duplicates")
async def with_duplicates(item: Item, item2: Item = Depends(duplicate_dependency)):
    return [item, item2]


@app.post("/no-duplicates")
async def no_duplicates(item: Item, item2: Item = Depends(dependency)):
    return [item, item2]


@app.post("/with-duplicates-sub")
async def no_duplicates_sub(

///

### Nicht-async *Pfadoperation-Funktionen* { #non-async-path-operation-functions }

Sie können auch normale `def`-Funktionen (ohne `async`) verwenden und `yield` auf die gleiche Weise einsetzen.

FastAPI stellt sicher, dass sie korrekt ausgeführt werden, sodass der Event Loop nicht blockiert wird.

Da die Funktion in diesem Fall nicht async ist, wäre der richtige Rückgabetyp `Iterable[Item]`:

@app.get("/items/{item_id}")
async def read_item(item_id: str):
    if item_id not in items:
        raise HTTPException(
            status_code=404,
            detail="Item not found",
            headers={"X-Error": "Some custom header"},
        )
    return {"item": items[item_id]}


@app.get("/http-no-body-statuscode-exception")
async def no_body_status_code_exception():