from typing import Union

from fastapi import FastAPI, Header
from pydantic import BaseModel

app = FastAPI()


class CommonHeaders(BaseModel):
    host: str
    save_data: bool
    if_modified_since: Union[str, None] = None
    traceparent: Union[str, None] = None
    x_tag: list[str] = []


@app.get("/items/")
async def read_items(headers: CommonHeaders = Header()):

from docs_src.python_types.tutorial013_py39 import say_hello


def test_say_hello():

import warnings

from fastapi import APIRouter, FastAPI
from fastapi.routing import APIRoute
from fastapi.testclient import TestClient
from pydantic import BaseModel


def custom_generate_unique_id(route: APIRoute):
    return f"foo_{route.name}"


def custom_generate_unique_id2(route: APIRoute):
    return f"bar_{route.name}"


def custom_generate_unique_id3(route: APIRoute):
    return f"baz_{route.name}"

## HTTPX { #httpx }

Auch wenn Ihre **FastAPI**-Anwendung normale `def`-Funktionen anstelle von `async def` verwendet, handelt es sich darunter immer noch um eine `async`-Anwendung.

from fastapi import FastAPI, Response, status

app = FastAPI()

tasks = {"foo": "Listen to the Bar Fighters"}


@app.put("/get-or-create-task/{task_id}", status_code=200)
def get_or_create_task(task_id: str, response: Response):
    if task_id not in tasks:
        tasks[task_id] = "This didn't exist before"
        response.status_code = status.HTTP_201_CREATED

Para decorar uma função com um único `yield`.

Isso é o que o **FastAPI** usa internamente para dependências com `yield`.

Mas você não precisa usar esses decoradores para as dependências do FastAPI (e você não deveria).

O FastAPI irá fazer isso para você internamente.

using them to decorate a function with a single `yield`.

That's what **FastAPI** uses internally for dependencies with `yield`.

But you don't have to use the decorators for FastAPI dependencies (and you shouldn't).

FastAPI will do it for you internally.

from typing import Union

from fastapi import FastAPI, status
from pydantic import BaseModel

app = FastAPI()


class Item(BaseModel):
    name: str
    description: Union[str, None] = None
    price: float
    tax: Union[float, None] = None
    tags: set[str] = set()


@app.post("/items/", response_model=Item, status_code=status.HTTP_201_CREATED)
async def create_item(item: Item):

### 使用 `app.dependency_overrides` 属性

对于这些用例，**FastAPI** 应用支持 `app.dependency_overrides` 属性，该属性就是**字典**。

要在测试时覆盖原有依赖项，这个字典的键应当是原依赖项（函数），值是覆盖依赖项（另一个函数）。

这样一来，**FastAPI** 就会调用覆盖依赖项，不再调用原依赖项。

{* ../../docs_src/dependency_testing/tutorial001_an_py310.py hl[26:27,30] *}

/// tip | 提示

**FastAPI** 应用中的任何位置都可以实现覆盖依赖项。

原依赖项可用于*路径操作函数*、*路径操作装饰器*（不需要返回值时）、`.include_router()` 调用等。

FastAPI 可以覆盖这些位置的依赖项。

///

- name: full-stack-fastapi-template
  html_url: https://github.com/fastapi/full-stack-fastapi-template
  stars: 39475
  owner_login: fastapi
  owner_html_url: https://github.com/fastapi
- name: Hello-Python
  html_url: https://github.com/mouredev/Hello-Python
  stars: 33090
  owner_login: mouredev
  owner_html_url: https://github.com/mouredev
- name: serve
  html_url: https://github.com/jina-ai/serve
  stars: 21798
  owner_login: jina-ai