* Validate that the `item_id` is of type `int` for `GET` and `PUT` requests.
    * If it is not, the client will see a useful, clear error.
* Check if there is an optional query parameter named `q` (as in `http://127.0.0.1:8000/items/foo?q=somequery`) for `GET` requests.
    * As the `q` parameter is declared with `= None`, it is optional.
    * Without the `None` it would be required (as is the body in the case with `PUT`).

app = FastAPI()


class Item(BaseModel):
    name: str
    description: str | None = None
    price: float
    tax: float = 10.5
    tags: list[str] = []


items = {
    "foo": {"name": "Foo", "price": 50.2},
    "bar": {"name": "Bar", "description": "The bartenders", "price": 62, "tax": 20.2},
    "baz": {"name": "Baz", "description": None, "price": 50.2, "tax": 10.5, "tags": []},
}

Das würde bedeuten, dass **FastAPI** einen Body wie folgt erwartet:

```JSON
{
    "name": "Foo",
    "description": "The pretender",
    "price": 42.0,
    "tax": 3.2,
    "tags": ["rock", "metal", "bar"],
    "image": {
        "url": "http://example.com/baz.jpg",
        "name": "The Foo live"
    }
}
```

Wiederum, nur mit dieser Deklaration erhalten Sie von **FastAPI**:

Bu da **FastAPI**’nin aşağıdakine benzer bir body bekleyeceği anlamına gelir:

```JSON
{
    "name": "Foo",
    "description": "The pretender",
    "price": 42.0,
    "tax": 3.2,
    "tags": ["rock", "metal", "bar"],
    "image": {
        "url": "http://example.com/baz.jpg",
        "name": "The Foo live"
    }
}
```

Yine, sadece bu tanımı yaparak **FastAPI** ile şunları elde edersiniz:

Значення параметра шляху `item_id` буде передано у вашу функцію як аргумент `item_id`.

Отже, якщо ви запустите цей приклад і перейдете за посиланням [http://127.0.0.1:8000/items/foo](http://127.0.0.1:8000/items/foo), то побачите відповідь:

```JSON
{"item_id":"foo"}
```

## Параметри шляху з типами { #path-parameters-with-types }

Ви можете оголосити тип параметра шляху у функції, використовуючи стандартні анотації типів Python:

   *   while (it.hasNext()) {
   *     foo(it.next());
   *   }
   * }
   * }
   *
   * <p>or:
   *
   * {@snippet :
   * NavigableMap<K, V> map = synchronizedNavigableMap(new TreeMap<K, V>());
   * NavigableMap<K, V> map2 = map.subMap(foo, false, bar, true);
   *
   * // Needn't be in synchronized block

{* ../../docs_src/header_params/tutorial003_an_py310.py hl[9] *}

Eğer bu *path operation* ile iki HTTP header göndererek iletişim kurarsanız:

```
X-Token: foo
X-Token: bar
```

response şöyle olur:

```JSON
{
    "X-Token values": [
        "bar",
        "foo"
    ]
}
```

## Özet { #recap }

Header'ları `Header` ile tanımlayın; `Query`, `Path` ve `Cookie` ile kullanılan ortak kalıbı burada da kullanın.

```JSON hl_lines="2"
{
    "item": {
        "name": "Foo",
        "description": "The pretender",
        "price": 42.0,
        "tax": 3.2
    }
}
```

au lieu de :

```JSON
{
    "name": "Foo",
    "description": "The pretender",
    "price": 42.0,
    "tax": 3.2
}
```

## Récapitulatif { #recap }

Testler:

## Code snippets { #code-snippets }

//// tab | Test

Bu bir code snippet: `foo`. Bu da başka bir code snippet: `bar`. Bir tane daha: `baz quux`.

////

//// tab | Bilgi

Code snippet'lerin içeriği olduğu gibi bırakılmalıdır.

La valeur du paramètre de chemin `item_id` sera transmise à votre fonction dans l'argument `item_id`.

Donc, si vous exécutez cet exemple et allez sur [http://127.0.0.1:8000/items/foo](http://127.0.0.1:8000/items/foo), vous verrez comme réponse :

```JSON
{"item_id":"foo"}
```

## Paramètres de chemin typés { #path-parameters-with-types }