from fastapi import FastAPI, Header

app = FastAPI()


@app.get("/items/")
async def read_items(user_agent: str | None = Header(default=None)):

        access = ServerMessageBlock.readInt4(buf, bi);
        bi += 4;
        sid = new SID(buf, bi);
        return size;
    }

    void appendCol(StringBuffer sb, String str, int width) {
        sb.append(str);
        int count = width - str.length();
        for (int i = 0; i < count; i++) {
            sb.append(' ');
        }
    }
    /**
     * Return a string represeting this ACE.
     * <p>

from fastapi import FastAPI, Header

app = FastAPI()


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

from fastapi import FastAPI, Query

app = FastAPI()


@app.get("/items/")
async def read_items(q: list[str] | None = Query(default=None)):
    query_items = {"q": q}

from fastapi import FastAPI, Request

app = FastAPI()


@app.get("/items/{item_id}")
def read_root(item_id: str, request: Request):
    client_host = request.client.host

from typing import Annotated

from fastapi import FastAPI, Header

app = FastAPI()


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

from typing import Annotated

from fastapi import FastAPI, Query

app = FastAPI()


@app.get("/items/")
async def read_items(q: Annotated[list[str], Query()] = ["foo", "bar"]):
    query_items = {"q": q}

    }

    public static String normalizeText(final String str, final int initialCapacity, final int maxAlphanumTermSize,
            final int maxSymbolTermSize, final boolean removeDuplication) {
        if (str == null) {
            return StringUtil.EMPTY;
        }
        try (final Reader reader = new StringReader(str)) {

否则，`/users/{user_id}` 将匹配 `/users/me`，FastAPI 会**认为**正在接收值为 `"me"` 的 `user_id` 参数。

## 预设值

路径操作使用 Python 的 <abbr title="Enumeration">`Enum`</abbr> 类型接收预设的*路径参数*。

### 创建 `Enum` 类

导入 `Enum` 并创建继承自 `str` 和 `Enum` 的子类。

通过从 `str` 继承，API 文档就能把值的类型定义为**字符串**，并且能正确渲染。

然后，创建包含固定值的类属性，这些固定值是可用的有效值：

```Python hl_lines="1  6-9"
{!../../docs_src/path_params/tutorial005.py!}
```

/// info | "说明"

from fastapi import FastAPI
from pydantic import BaseModel, HttpUrl

app = FastAPI()


class Image(BaseModel):
    url: HttpUrl
    name: str


@app.post("/images/multiple/")
async def create_multiple_images(images: list[Image]):