由于路径首先匹配，始终会使用第一个定义的。

## 预设值 { #predefined-values }

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

### 创建 `Enum` 类 { #create-an-enum-class }

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_py310.py hl[1,6:9] *}

/// tip | 提示

    @Override
    public List<Character> create(Character[] elements) {
      char[] chars = Chars.toArray(asList(elements));
      StringBuilder str = new StringBuilder();
      str.append(chars);
      return charactersOf(str);
    }
  }

  public static class UnhashableElementsImmutableListGenerator
      extends TestUnhashableCollectionGenerator<List<UnhashableObject>>

form of JUnit-based XML.
"""
import argparse
import datetime
import os
import re
from typing import Dict, Union
import xml.etree.ElementTree as ElemTree


ResultDictType = Dict[str, Dict[str, Union[str, int]]]

RESULT_STORE_LINK_RE = re.compile(
    r'^INFO: Streaming build results to: (https://[\w./\-]+)')
FAILED_BUILD_LINE = 'FAILED: Build did NOT complete successfully'
BUILD_STATUS_LINE = 'INFO: Build'

from fastapi import FastAPI
from fastapi.testclient import TestClient
from inline_snapshot import snapshot


@dataclass
class Item:
    id: uuid.UUID
    name: str
    price: float
    tags: list[str] = field(default_factory=list)
    description: str | None = None
    tax: float | None = None


app = FastAPI()


@app.get("/item", response_model=Item)
async def read_item():
    return {

    def __get_pydantic_json_schema__(
        cls, core_schema: Mapping[str, Any], handler: GetJsonSchemaHandler
    ) -> dict[str, Any]:
        return {"type": "string", "contentMediaType": "application/octet-stream"}

    @classmethod
    def __get_pydantic_core_schema__(
        cls, source: type[Any], handler: Callable[[Any], Mapping[str, Any]]
    ) -> Mapping[str, Any]:
        from ._compat.v2 import with_info_plain_validator_function

import uuid

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


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):

    // Or, more simply, check the format of the string.
    @Test
    void testToStringFormat() {
        String str = response.toString();
        assert (str.startsWith("TransTransactNamedPipeResponse["));
        assert (str.endsWith("]"));
    }
}

// We need to add a helper method to TransTransactNamedPipeResponse to make the test more precise

@router.get("/{item_id}")
async def read_item(item_id: str):
    if item_id not in fake_items_db:
        raise HTTPException(status_code=404, detail="Item not found")
    return {"name": fake_items_db[item_id]["name"], "item_id": item_id}


@router.put(
    "/{item_id}",
    tags=["custom"],
    responses={403: {"description": "Operation forbidden"}},
)
async def update_item(item_id: str):
    if item_id != "plumbus":

from pydantic import BaseModel

app = FastAPI()


class JsonApiResponse(JSONResponse):
    media_type = "application/vnd.api+json"


class Error(BaseModel):
    status: str
    title: str


class JsonApiError(BaseModel):
    errors: list[Error]


@app.get(
    "/a",
    response_class=Response,
    responses={500: {"description": "Error", "model": JsonApiError}},
)

from inline_snapshot import snapshot
from pydantic import BaseModel

app = FastAPI()

oid = OpenIdConnect(openIdConnectUrl="/openid")


class User(BaseModel):
    username: str


def get_current_user(oauth_header: str = Security(oid)):
    user = User(username=oauth_header)
    return user


@app.get("/users/me")
def read_current_user(current_user: User = Depends(get_current_user)):
    return current_user