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):

        .build()
    host = "${server.hostName}:${server.port}"
    url = server.url("/")
  }

  @Test
  fun levelGetter() {
    // The default is NONE.
    assertThat(applicationInterceptor.level).isEqualTo(Level.NONE)
    for (level in Level.entries) {
      applicationInterceptor.setLevel(level)
      assertThat(applicationInterceptor.level).isEqualTo(level)
    }
  }

  @Test

```Python
q: Union[str, None] = None
```

Ou bien, en Python 3.10 et supérieur :

```Python
q: str | None = None
```

Par exemple :

{* ../../docs_src/body_multiple_params/tutorial004_an_py310.py hl[27] *}

/// info

デフォルト値`None`を`Query(default=None)`に置き換える必要があるので、`Query`の最初の引数はデフォルト値を定義するのと同じです。

なので:

```Python
q: Optional[str] = Query(default=None)
```

...を以下と同じようにパラメータをオプションにします:

```Python
q: Optional[str] = None
```

しかし、これはクエリパラメータとして明示的に宣言しています。

/// info | 情報

FastAPIは以下の部分を気にすることを覚えておいてください:

```Python
= None
```

もしくは:

```Python

		// Baremetal setups set DNS refresh window up to dnsTTL duration.
		t := time.NewTicker(dnsTTL)
		defer t.Stop()
		for {
			select {
			case <-t.C:
				globalDNSCache.Refresh()

			case <-GlobalContext.Done():
				return
			}
		}
	}()
}

type envKV struct {
	Key   string
	Value string
	Skip  bool
}

func (e envKV) String() string {
	if e.Skip {
		return ""
	}

## 💗 💪 = & 🔢

↗️, 👆 💪 📣 🌖 🔢 🔢 🕐❔ 👆 💪, 🌖 🙆 💪 🔢.

, 🔢, ⭐ 💲 🔬 🔢 🔢, 👆 🚫 ✔️ 🎯 🚮 `Query`, 👆 💪:

```Python
q: Union[str, None] = None
```

⚖️ 🐍 3️⃣.1️⃣0️⃣ & 🔛:

```Python
q: str | None = None
```

🖼:

{* ../../docs_src/body_multiple_params/tutorial004.py hl[27] *}

/// info

Como, por defecto, los valores singulares se interpretan como parámetros de query, no tienes que añadir explícitamente un `Query`, solo puedes hacer:

```Python
q: Union[str, None] = None
```

O en Python 3.10 y superior:

```Python
q: str | None = None
```

Por ejemplo:

{* ../../docs_src/body_multiple_params/tutorial004_an_py310.py hl[28] *}

/// info | Información

    assertThat(get(url).body.string()).isEqualTo("B")
    assertThat(server.takeRequest().headers["If-None-Match"]).isNull()
    assertThat(server.takeRequest().headers["If-None-Match"]).isEqualTo("v1")
    assertThat(server.takeRequest().headers["If-None-Match"]).isEqualTo("v1")
    assertThat(server.takeRequest().headers["If-None-Match"]).isEqualTo("v2")
  }

  @Test
  fun combinedCacheHeadersCanBeNonAscii() {

              }

              // timed out?
              remainingNanos = endNanos - System.nanoTime();
              if (remainingNanos < SPIN_THRESHOLD_NANOS) {
                // Remove the waiter, one way or another we are done parking this thread.
                removeWaiter(node);
                break long_wait_loop; // jump down to the busy wait loop
              }
            }
          }

🎏 🕐❔ 📣 🔢 🔢, 🕐❔ 🏷 🔢 ✔️ 🔢 💲, ⚫️ 🚫 ✔. ⏪, ⚫️ ✔. ⚙️ `None` ⚒ ⚫️ 📦.

🖼, 👉 🏷 🔛 📣 🎻 "`object`" (⚖️ 🐍 `dict`) 💖:

```JSON
{
    "name": "Foo",
    "description": "An optional description",
    "price": 45.2,
    "tax": 3.5
}
```

... `description` & `tax` 📦 (⏮️ 🔢 💲 `None`), 👉 🎻 "`object`" 🔜 ☑:

```JSON
{
    "name": "Foo",
    "price": 45.2
}
```