例如，要宣告可以出現多次的 `X-Token` 標頭，可以這樣寫：

{* ../../docs_src/header_params/tutorial003_an_py310.py hl[9] *}

如果你在與該*路徑操作 (path operation)* 溝通時送出兩個 HTTP 標頭如下：

```
X-Token: foo
X-Token: bar
```

回應會像這樣：

```JSON
{
    "X-Token values": [
        "bar",
        "foo"
    ]
}
```

## 小結 { #recap }

使用 `Header` 宣告標頭，套用與 `Query`、`Path`、`Cookie` 相同的通用模式。

from fastapi import FastAPI
from pydantic import BaseModel, Field

app = FastAPI()


class Item(BaseModel):
    name: str = Field(examples=["Foo"])
    description: str | None = Field(default=None, examples=["A very nice Item"])
    price: float = Field(examples=[35.4])
    tax: float | None = Field(default=None, examples=[3.2])


@app.put("/items/{item_id}")
async def update_item(item_id: int, item: Item):

    description: str | None = None
    price: float
    tax: float | None = None

    model_config = {
        "json_schema_extra": {
            "examples": [
                {
                    "name": "Foo",
                    "description": "A very nice Item",
                    "price": 35.4,
                    "tax": 3.2,
                }
            ]
        }
    }


@app.put("/items/{item_id}")

from fastapi import FastAPI
from fastapi.routing import APIRoute

app = FastAPI()


@app.get("/items/")
async def read_items():
    return [{"item_id": "Foo"}]


def use_route_names_as_operation_ids(app: FastAPI) -> None:
    """
    Simplify operation IDs so that generated API clients have simpler function
    names.

    Should be called only after all routes have been added.
    """
    for route in app.routes:

        min_length=3,
        max_length=50,
        pattern="^fixedquery$",
        deprecated=True,
    ),
):
    results = {"items": [{"item_id": "Foo"}, {"item_id": "Bar"}]}
    if q:
        results.update({"q": q})

from typing import Annotated, Any

from fastapi import Depends, FastAPI

app = FastAPI()


fake_items_db = [{"item_name": "Foo"}, {"item_name": "Bar"}, {"item_name": "Baz"}]


class CommonQueryParams:
    def __init__(self, q: str | None = None, skip: int = 0, limit: int = 100):
        self.q = q
        self.skip = skip
        self.limit = limit


@app.get("/items/")

        raise HTTPException(status_code=400, detail="X-Key header invalid")
    return x_key


@app.get("/items/", dependencies=[Depends(verify_token), Depends(verify_key)])
async def read_items():

from fastapi import FastAPI, Query

app = FastAPI()


@app.get("/items/")
async def read_items(q: str = Query(min_length=3)):
    results = {"items": [{"item_id": "Foo"}, {"item_id": "Bar"}]}
    if q:
        results.update({"q": q})

    assertThat(Ascii.truncate("foobar", 4, "…")).isEqualTo("foo…");
    assertThat(Ascii.truncate("foobar", 4, "--")).isEqualTo("fo--");
    assertThat(Ascii.truncate("foobar", 6, "…")).isEqualTo("foobar");
    assertThat(Ascii.truncate("foobar", 5, "…")).isEqualTo("foob…");
    assertThat(Ascii.truncate("foobar", 3, "")).isEqualTo("foo");
    assertThat(Ascii.truncate("", 5, "")).isEqualTo("");

    assertThat(Ascii.truncate("foobar", 4, "…")).isEqualTo("foo…");
    assertThat(Ascii.truncate("foobar", 4, "--")).isEqualTo("fo--");
    assertThat(Ascii.truncate("foobar", 6, "…")).isEqualTo("foobar");
    assertThat(Ascii.truncate("foobar", 5, "…")).isEqualTo("foob…");
    assertThat(Ascii.truncate("foobar", 3, "")).isEqualTo("foo");
    assertThat(Ascii.truncate("", 5, "")).isEqualTo("");