if tc.error == "" && err != nil {
				t.Fatalf("expected no error, got %v", err)
			}
			if tc.error != "" {
				if err == nil {
					t.Fatalf("expected error to include \"%s\" but got none", tc.error)
				}
				if !strings.Contains(err.Error(), tc.error) {
					t.Fatalf("expected \"%s\" in error, got %v", tc.error, err)
				}
			}

			commandOutput := out.String()

(prefers-reduced-motion: reduce) {\n  .btn {\n    transition: none;\n  }\n}\n\n.btn:hover {\n  color: #212529;\n  text-decoration: none;\n}\n\n.btn:focus, .btn.focus {\n  outline: 0;\n  box-shadow: none;\n}\n\n.btn.disabled, .btn:disabled {\n  opacity: 0.65;\n  box-shadow: none;\n}\n\n.btn:not(:disabled):not(.disabled) {\n  cursor: pointer;\n}\n\n.btn:not(:disabled):not(.disabled):active, .btn:not(:disabled):not(.disabled).active {\n  box-shadow: none;\n}\n\na.btn.disabled,\nfieldset:disabled a.btn {\n  pointer-events:...

    response = client.post("/items/", json={"name": "Foo", "price": 3})
    assert response.status_code == 200
    assert response.json() == {
        "name": "Foo",
        "price": 3,
        "description": None,
        "tax": None,
    }


def test_post_invalid_item():
    response = client.post("/items/", json={"name": "Foo", "price": "invalid price"})
    assert response.status_code == 422
    assert response.json() == IsDict(

    response = client.get("/users/")
    assert response.status_code == 200, response.text
    assert response.json() == {
        "message": "Hello Users!",
        "params": {"q": None, "skip": 5, "limit": 10},
    }


@needs_py310
def test_override_in_users_with_q():
    from docs_src.dependency_testing.tutorial001_py310 import client

    response = client.get("/users/?q=foo")

Fonksiyonunuzdaki parametre değerleri aşağıdaki gibi olacaktır:

* `skip=20`: çünkü bağlantıda böyle tanımlandı.
* `limit=10`: çünkü varsayılan değer buydu.

## İsteğe Bağlı Parametreler

Aynı şekilde, varsayılan değerlerini `None` olarak atayarak isteğe bağlı parametreler tanımlayabilirsiniz:

//// tab | Python 3.10+

```Python hl_lines="7"
{!> ../../docs_src/query_params/tutorial002_py310.py!}
```

////

//// tab | Python 3.8+

## 📦 🔢

🎏 🌌, 👆 💪 📣 📦 🔢 🔢, ⚒ 👫 🔢 `None`:

//// tab | 🐍 3️⃣.6️⃣ & 🔛

```Python hl_lines="9"
{!> ../../docs_src/query_params/tutorial002.py!}
```

////

//// tab | 🐍 3️⃣.1️⃣0️⃣ & 🔛

```Python hl_lines="7"
{!> ../../docs_src/query_params/tutorial002_py310.py!}
```

////

👉 💼, 🔢 🔢 `q` 🔜 📦, & 🔜 `None` 🔢.

/// check

</div>

Isso significa que ele **sempre terá um valor**, só que às vezes o valor pode ser `None` (ou `null` em termos de JSON).

Isso quer dizer que, os clientes que usam sua API não precisam verificar se o valor existe ou não, eles podem **assumir que o campo sempre estará lá**, mas que em alguns casos terá o valor padrão de `None`.

A maneira de descrever isso no OpenAPI é marcar esse campo como **obrigatório**, porque ele sempre estará lá.

        {
            "detail": [
                {
                    "type": "missing",
                    "loc": ["body", "file"],
                    "msg": "Field required",
                    "input": None,
                }
            ]
        }
    ) | IsDict(
        # TODO: remove when deprecating Pydantic v1
        {
            "detail": [
                {
                    "loc": ["body", "file"],

        {
            "detail": [
                {
                    "type": "missing",
                    "loc": ["body", "file"],
                    "msg": "Field required",
                    "input": None,
                }
            ]
        }
    ) | IsDict(
        # TODO: remove when deprecating Pydantic v1
        {
            "detail": [
                {
                    "loc": ["body", "file"],

app = FastAPI()


class Item(BaseModel):
    name: str
    price: float
    is_offer: Union[bool, None] = None


@app.get("/")
def read_root():
    return {"Hello": "World"}


@app.get("/items/{item_id}")
def read_item(item_id: int, q: Union[str, None] = None):
    return {"item_id": item_id, "q": q}


@app.put("/items/{item_id}")
def update_item(item_id: int, item: Item):