# 高级 Python 类型 { #advanced-python-types }

这里有一些在使用 Python 类型时可能有用的额外想法。

## 使用 `Union` 或 `Optional` { #using-union-or-optional }

如果你的代码因为某些原因不能使用 `|`，例如它不是在类型注解里，而是在 `response_model=` 之类的参数中，那么你可以使用 `typing` 中的 `Union` 来代替竖线（`|`）。

例如，你可以声明某个值可以是 `str` 或 `None`：

```python
from typing import Union


def say_hi(name: Union[str, None]):
        print(f"Hi {name}!")
```

`typing` 也提供了一个声明“可能为 `None`”的快捷方式：`Optional`。

# 高度な Python の型 { #advanced-python-types }

Python の型を扱うときに役立つ追加のアイデアをいくつか紹介します。

## `Union` または `Optional` の利用 { #using-union-or-optional }

何らかの理由で `|` が使えない場合、たとえば型アノテーションではなく `response_model=` のような場所では、縦棒（`|`）の代わりに `typing` の `Union` を使えます。

例えば、`str` または `None` になり得ることを宣言できます:

```python
from typing import Union


def say_hi(name: Union[str, None]):
        print(f"Hi {name}!")
```

        return True
    origin = get_origin(annotation)
    if origin is Union or origin is UnionType:
        for arg in get_args(annotation):
            if lenient_issubclass(arg, UploadFile):
                return True
    return False


def is_bytes_sequence_annotation(annotation: Any) -> bool:
    origin = get_origin(annotation)
    if origin is Union or origin is UnionType:
        at_least_one = False

## `Union` or `anyOf` { #union-or-anyof }

You can declare a response to be the `Union` of two or more types, that means, that the response would be any of them.

It will be defined in OpenAPI with `anyOf`.

To do that, use the standard Python type hint [`typing.Union`](https://docs.python.org/3/library/typing.html#typing.Union):

/// note

                                    "application/json": {
                                        "schema": {
                                            "title": "Response Response Model Union No Annotation Return Model1 Response Model Union No Annotation Return Model1 Get",
                                            "anyOf": [
                                                {"$ref": "#/components/schemas/User"},

Python 타입을 다룰 때 유용할 수 있는 몇 가지 추가 아이디어를 소개합니다.

## `Union` 또는 `Optional` 사용 { #using-union-or-optional }

어떤 이유로 코드에서 `|`를 사용할 수 없다면, 예를 들어 타입 어노테이션이 아니라 `response_model=` 같은 곳이라면, 파이프 문자(`|`) 대신 `typing`의 `Union`을 사용할 수 있습니다.

예를 들어, 어떤 값이 `str` 또는 `None`이 될 수 있다고 선언할 수 있습니다:

```python
from typing import Union


def say_hi(name: Union[str, None]):
        print(f"Hi {name}!")
```

def test_serialize_sequence_value_with_none_first_in_union():
    """Test that serialize_sequence_value handles Union[None, List[...]] correctly."""
    from typing import Union

    from fastapi._compat import v2

    # Use Union[None, list[str]] to ensure None comes first in the union args
    field_info = FieldInfo(annotation=Union[None, list[str]])  # noqa: UP007
    field = v2.ModelField(name="items", field_info=field_info)

#### Union { #union }

You can declare that a variable can be any of **several types**, for example, an `int` or a `str`.

To define it you use the <dfn title='also called "bitwise or operator", but that meaning is not relevant here'>vertical bar (`|`)</dfn> to separate both types.

This is called a "union", because the variable can be anything in the union of those two sets of types.

def is_union_of_base_models(field_type: Any) -> bool:
    """Check if field type is a Union where all members are BaseModel subclasses."""
    from fastapi.types import UnionType

    origin = get_origin(field_type)

    # Check if it's a Union type (covers both typing.Union and types.UnionType in Python 3.10+)
    if origin is not Union and origin is not UnionType:
        return False

    union_args = get_args(field_type)

        : result;
  }

  /**
   * Returns a new range set consisting of the union of this range set and {@code other}.
   *
   * <p>This is essentially the same as {@code TreeRangeSet.create(this).addAll(other)} except it
   * returns an {@code ImmutableRangeSet}.
   *
   * @since 21.0
   */
  public ImmutableRangeSet<C> union(RangeSet<C> other) {
    return unionOf(Iterables.concat(asRanges(), other.asRanges()));
  }