session: Annotated[Union[str, None], Cookie()] = None,
    token: Annotated[Union[str, None], Query()] = None,
):
    if session is None and token is None:
        raise WebSocketException(code=status.WS_1008_POLICY_VIOLATION)
    return session or token


@app.websocket("/items/{item_id}/ws")
async def websocket_endpoint(
    *,
    websocket: WebSocket,
    item_id: str,
    q: Union[int, None] = None,

import pytest
from fastapi import FastAPI
from fastapi.testclient import TestClient
from pydantic import BaseModel

from .utils import needs_pydanticv1, needs_pydanticv2


class MyUuid:
    def __init__(self, uuid_string: str):
        self.uuid = uuid_string

    def __str__(self):
        return self.uuid

    @property  # type: ignore
    def __class__(self):
        return uuid.UUID

    @property
    def __dict__(self):

Linux-like paths MSYS uses, for example, Docker.
"""

import argparse
import os


def should_convert(var_name: str,
                   blacklist: list[str] | None,
                   whitelist_prefix: list[str] | None):
  """Check the variable name against white/black lists."""
  if blacklist and var_name in blacklist:
    return False
  if not whitelist_prefix:
    return True

    websocket: WebSocket,
    session: Union[str, None] = Cookie(default=None),
    token: Union[str, None] = Query(default=None),
):
    if session is None and token is None:
        raise WebSocketException(code=status.WS_1008_POLICY_VIOLATION)
    return session or token


@app.websocket("/items/{item_id}/ws")
async def websocket_endpoint(
    websocket: WebSocket,
    item_id: str,
    q: Union[int, None] = None,

/// check | "检查"

注意，**FastAPI** 可以识别出 `item_id` 是路径参数，`q` 不是路径参数，而是查询参数。

///

/// note | "笔记"

因为默认值为 `= None`，FastAPI 把 `q` 识别为可选参数。

FastAPI 不使用 `Optional[str]` 中的 `Optional`（只使用 `str`），但 `Optional[str]` 可以帮助编辑器发现代码中的错误。

///

## 查询参数类型转换

参数还可以声明为 `bool` 类型，FastAPI 会自动转换参数类型：


//// tab | Python 3.10+

```Python hl_lines="7"

from typing import Union

from fastapi import Body, FastAPI
from pydantic import BaseModel

app = FastAPI()


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


@app.put("/items/{item_id}")
async def update_item(
    item_id: int,
    item: Item = Body(
        examples=[
            {
                "name": "Foo",

Vamos a cambiar exactamente este fragmento, los parámetros de la función, de:

```Python
    first_name, last_name
```

a:

```Python
    first_name: str, last_name: str
```

Eso es todo.

Esos son los "type hints":

```Python hl_lines="1"
{!../../docs_src/python_types/tutorial002.py!}
```

No es lo mismo a declarar valores por defecto, como sería con:

* Überreichen Sie den/die inneren Typ(en) von eckigen Klammern umschlossen, `[` und `]`, als „Typ-Parameter“

In Python 3.9 wäre das:

```Python
my_list: list[str]
```

Und in Python-Versionen vor 3.9:

```Python
from typing import List

my_list: List[str]
```

Das ist alles Standard-Python-Syntax für Typdeklarationen.

Verwenden Sie dieselbe Standardsyntax für Modellattribute mit inneren Typen.

    /**
     * ブランクかどうか返します。
     *
     * @param str
     *            文字列
     * @return ブランクなら{@literal true}
     */
    public static boolean isBlank(final String str) {
        if (str == null || str.length() == 0) {
            return true;
        }
        for (int i = 0; i < str.length(); i++) {
            if (!Character.isWhitespace(str.charAt(i))) {
                return false;
            }

def get_name_with_age(name: str, age: int):
    name_with_age = name + " is this old: " + str(age)