También podrías usarlo para generar código automáticamente, para los clientes que se comunican con tu API. Por ejemplo, frontend, móvil o aplicaciones de IoT.

## Repaso, paso a paso

### Paso 1: importa `FastAPI`

```Python hl_lines="1"
{!../../docs_src/first_steps/tutorial001.py!}
```

from fastapi import FastAPI
from fastapi.openapi.utils import get_openapi

app = FastAPI()


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


def custom_openapi():
    if app.openapi_schema:
        return app.openapi_schema
    openapi_schema = get_openapi(
        title="Custom title",
        version="2.5.0",
        summary="This is a very custom OpenAPI schema",

from fastapi import FastAPI
from fastapi.testclient import TestClient

app = FastAPI()


@app.get("/", openapi_extra={"x-custom-extension": "value"})
def route_with_extras():
    return {}


client = TestClient(app)


def test_get_route():
    response = client.get("/")
    assert response.status_code == 200, response.text
    assert response.json() == {}


def test_openapi():

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

app = FastAPI()


@app.get("/a", responses={"hello": {"description": "Not a valid additional response"}})
async def a():
    pass  # pragma: no cover


openapi_schema = {
    "openapi": "3.1.0",
    "info": {"title": "FastAPI", "version": "0.1.0"},
    "paths": {
        "/a": {
            "get": {
                "responses": {

from fastapi import FastAPI, Request
from fastapi.responses import HTMLResponse
from fastapi.staticfiles import StaticFiles
from fastapi.templating import Jinja2Templates

app = FastAPI()

app.mount("/static", StaticFiles(directory="static"), name="static")


templates = Jinja2Templates(directory="templates")


@app.get("/items/{id}", response_class=HTMLResponse)
async def read_item(request: Request, id: str):

///

**FastAPI** 🔜 🏧 🛠️ ⚪️➡️ 📨, 👈 🔢 `item` 📨 ⚫️ 🎯 🎚 & 🎏 `user`.

⚫️ 🔜 🎭 🔬 ⚗ 💽, & 🔜 📄 ⚫️ 💖 👈 🗄 🔗 & 🏧 🩺.

## ⭐ 💲 💪

🎏 🌌 📤 `Query` & `Path` 🔬 ➕ 💽 🔢 & ➡ 🔢, **FastAPI** 🚚 🌓 `Body`.

🖼, ↔ ⏮️ 🏷, 👆 💪 💭 👈 👆 💚 ✔️ ➕1️⃣ 🔑 `importance` 🎏 💪, 🥈 `item` & `user`.

🚥 👆 📣 ⚫️, ↩️ ⚫️ ⭐ 💲, **FastAPI** 🔜 🤔 👈 ⚫️ 🔢 🔢.

`Response` 매개변수를 사용하지 않고 응답을 직접 반환하는 경우, FastAPI는 이를 직접 반환한다는 점에 유의하세요.

따라서 데이터가 올바른 유형인지 확인해야 합니다. 예: `JSONResponse`를 반환하는 경우, JSON과 호환되는지 확인하세요.

또한 `response_model`로 걸러져야 할 데이터가 전달되지 않도록 확인하세요.

///

### 추가 정보

/// note | "기술적 세부사항"

`from starlette.responses import Response` 또는 `from starlette.responses import JSONResponse`를 사용할 수도 있습니다.

...
```

#### OpenAPI 的用途

驱动 FastAPI 内置的 2 个交互式文档系统的正是 OpenAPI 模式。

并且还有数十种替代方案，它们全部都基于 OpenAPI。你可以轻松地将这些替代方案中的任何一种添加到使用 **FastAPI** 构建的应用程序中。

你还可以使用它自动生成与你的 API 进行通信的客户端代码。例如 web 前端，移动端或物联网嵌入程序。

## 分步概括

### 步骤 1：导入 `FastAPI`

```Python hl_lines="1"
{!../../docs_src/first_steps/tutorial001.py!}
```

`FastAPI` 是一个为你的 API 提供了所有功能的 Python 类。

/// note | "技术细节"

from fastapi import Depends, FastAPI
from fastapi.requests import HTTPConnection
from fastapi.testclient import TestClient
from starlette.websockets import WebSocket

app = FastAPI()
app.state.value = 42


async def extract_value_from_http_connection(conn: HTTPConnection):
    return conn.app.state.value


@app.get("/http")
async def get_value_by_http(value: int = Depends(extract_value_from_http_connection)):
    return value

## GraphQL Libraries

Here are some of the **GraphQL** libraries that have **ASGI** support. You could use them with **FastAPI**:

* <a href="https://strawberry.rocks/" class="external-link" target="_blank">Strawberry</a> 🍓
    * With <a href="https://strawberry.rocks/docs/integrations/fastapi" class="external-link" target="_blank">docs for FastAPI</a>
* <a href="https://ariadnegraphql.org/" class="external-link" target="_blank">Ariadne</a>