@Override
        Optional<String> chop(String str) {
          return i.chop(str).or(you.chop(str));
        }
      };
    }

    abstract Optional<String> chop(String str);

    static Chopper suffix(String suffix) {
      return new Chopper() {
        @Override
        Optional<String> chop(String str) {
          if (str.endsWith(suffix)) {

from fastapi import FastAPI

app = FastAPI()


@app.post("/items/", status_code=201)
async def create_item(name: str):

from fastapi import FastAPI, Header

app = FastAPI()


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

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：

{* ../../docs_src/path_params/tutorial005.py hl[1,6:9] *}

/// info | 说明

### Crie uma classe `Enum` { #create-an-enum-class }

Importe `Enum` e crie uma subclasse que herde de `str` e de `Enum`.

Ao herdar de `str`, a documentação da API saberá que os valores devem ser do tipo `string` e poderá renderizá-los corretamente.

Em seguida, crie atributos de classe com valores fixos, que serão os valores válidos disponíveis:

      public void write(char[] cbuf, int off, int len) throws IOException {
        super.write(cbuf, off, len);
        flush();
      }

      @Override
      public void write(String str, int off, int len) throws IOException {
        super.write(str, off, len);
        flush();
      }
    };
  }

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}

    @DisplayName("Test toString contains proper class name")
    void testToStringFormat() {
        String str = response.toString();

        // Should start with the class name
        assertTrue(str.startsWith("Trans2SetFileInformationResponse["));

        // Should end with closing bracket
        assertTrue(str.endsWith("]"));

        // Should contain parent toString content

from fastapi import FastAPI
from pydantic.v1 import BaseSettings


class Settings(BaseSettings):
    app_name: str = "Awesome API"
    admin_email: str
    items_per_user: int = 50


settings = Settings()
app = FastAPI()


@app.get("/info")
async def info():
    return {
        "app_name": settings.app_name,
        "admin_email": settings.admin_email,
        "items_per_user": settings.items_per_user,