from fastapi import FastAPI

app = FastAPI()


@app.get("/items/")
async def read_items(q: str | None = None):
    results = {"items": [{"item_id": "Foo"}, {"item_id": "Bar"}]}
    if q:
        results.update({"q": q})

from typing import Annotated, Union

from fastapi import FastAPI, Header

app = FastAPI()


@app.get("/items/")
async def read_items(
    strange_header: Annotated[
        Union[str, None], Header(convert_underscores=False)
    ] = None,
):

from fastapi import FastAPI, Query

app = FastAPI()


@app.get("/items/")
async def read_items(
    hidden_query: str | None = Query(default=None, include_in_schema=False),
):
    if hidden_query:
        return {"hidden_query": hidden_query}
    else:

from typing import List, Union

from fastapi import FastAPI, Header

app = FastAPI()


@app.get("/items/")
async def read_items(x_token: Union[List[str], None] = Header(default=None)):

@app.get("/items/{item_id}", response_model=Item)
async def read_main(item_id: str, x_token: str = Header()):
    if x_token != fake_secret_token:
        raise HTTPException(status_code=400, detail="Invalid X-Token header")
    if item_id not in fake_db:
        raise HTTPException(status_code=404, detail="Item not found")
    return fake_db[item_id]


@app.post("/items/", response_model=Item)
async def create_item(item: Item, x_token: str = Header()):

        ("/users/", 200, [{"username": "johndoe"}]),
        ("/elements/", 200, [{"item_id": "Foo"}]),
    ],
)
def test_query_params_str_validations(path, expected_status, expected_response):
    response = client.get(path)
    assert response.status_code == expected_status
    assert response.json() == expected_response


def test_openapi_schema():
    response = client.get("/openapi.json")
    assert response.status_code == 200, response.text

from typing import Annotated, List, Union

from fastapi import FastAPI, Header

app = FastAPI()


@app.get("/items/")
async def read_items(x_token: Annotated[Union[List[str], None], Header()] = None):

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">
<summary>또는 <code>async def</code> 사용하기...</summary>

여러분의 코드가 `async` / `await`을 사용한다면, `async def`를 사용하십시오.

```Python hl_lines="9 14"

from typing import Union

from fastapi import FastAPI

app = FastAPI()


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

from pydantic import BaseModel


class Item(BaseModel):
    name: str
    description: str | None = None
    price: float
    tax: float | None = None


app = FastAPI()


@app.post("/items/")
async def create_item(item: Item):