POLICY_INFO_PRIMARY_DOMAIN = 3,
		POLICY_INFO_ACCOUNT_DOMAIN = 5,
		POLICY_INFO_SERVER_ROLE    = 6,
		POLICY_INFO_MODIFICATION   = 9,
		POLICY_INFO_DNS_DOMAIN     = 12
	};

	typedef [switch_type(short)] union {
		[case(POLICY_INFO_ACCOUNT_DOMAIN)] LsarDomainInfo account_domain;
		[case(POLICY_INFO_DNS_DOMAIN)] LsarDnsDomainInfo dns_domain;
	} LsarPolicyInfo;

	typedef struct {
		sid_t *sid;
	} LsarSidPtr;

		POLICY_INFO_PRIMARY_DOMAIN = 3,
		POLICY_INFO_ACCOUNT_DOMAIN = 5,
		POLICY_INFO_SERVER_ROLE    = 6,
		POLICY_INFO_MODIFICATION   = 9,
		POLICY_INFO_DNS_DOMAIN     = 12
	};

	typedef [switch_type(short)] union {
		[case(POLICY_INFO_ACCOUNT_DOMAIN)] LsarDomainInfo account_domain;
		[case(POLICY_INFO_DNS_DOMAIN)] LsarDnsDomainInfo dns_domain;
	} LsarPolicyInfo;

	typedef struct {
		sid_t *sid;
	} LsarSidPtr;

/// note | Observação

O FastAPI saberá que o valor de `q` não é obrigatório por causa do valor padrão `= None`.

O `Union` em `Union[str, None]` não é utilizado pelo FastAPI, mas permite ao seu editor de texto lhe dar um suporte melhor e detectar erros.

///

## Sem o Pydantic

/// note

FastAPI will know that the value of `q` is not required because of the default value `= None`.

The `str | None` (Python 3.10+) or `Union` in `Union[str, None]` (Python 3.8+) is not used by FastAPI to determine that the value is not required, it will know it's not required because it has a default value of `= None`.

То же самое произошло бы, если бы у вас было что-то вроде <abbr title='Union разных типов буквально означает "любой из перечисленных типов".'>Union</abbr> различных типов и один или несколько из них не являлись бы допустимыми типами для Pydantic. Например, такой вариант приведет к ошибке 💥:

q: str | None = None
```

////

//// tab | Python 3.8+

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

////

What we will do is wrap that with `Annotated`, so it becomes:

//// tab | Python 3.10+

```Python
q: Annotated[str | None] = None
```

////

//// tab | Python 3.8+

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

////

        try {
          BigInteger quotient = BigIntegerMath.divide(p, q, UNNECESSARY);
          BigInteger undone = quotient.multiply(q);
          if (!p.equals(undone)) {
            failFormat("expected %s.multiply(%s) = %s; got %s", quotient, q, p, undone);
          }
          assertTrue(dividesEvenly);
        } catch (ArithmeticException e) {
          assertFalse(dividesEvenly);
        }

### ایجاد کنید
* فایلی به نام `main.py` با محتوای زیر ایجاد کنید:

```Python
from typing import Union

from fastapi import FastAPI

app = FastAPI()


@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}
```

<details markdown="1">

        }

        @Override
        public void decode_out(NdrBuffer _src) throws NdrException {
            this.level = _src.dec_ndr_long();
            _src.dec_ndr_long(); /* union discriminant */
            final int _infop = _src.dec_ndr_long();
            if (_infop != 0) {
                if (this.info == null) { /* YOYOYO */
                    this.info = new ShareInfoCtr0();

## 必須にする

これ以上、バリデーションやメタデータを宣言する必要のない場合は、デフォルト値を指定しないだけでクエリパラメータ`q`を必須にすることができます。以下のように:

```Python
q: str
```

以下の代わりに:

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

現在は以下の例のように`Query`で宣言しています:

```Python
q: Union[str, None] = Query(default=None, min_length=3)
```

そのため、`Query`を使用して必須の値を宣言する必要がある場合は、第一引数に`...`を使用することができます: