* **FastAPI**:
    * 与 Starlette 使用 Uvicorn 一样，由于 **FastAPI** 使用 Starlette，因此 FastAPI 不能比 Starlette 更快。
    * FastAPI 在 Starlette 基础上提供了更多功能。例如在开发 API 时，所需的数据验证和序列化功能。FastAPI 可以帮助您自动生成 API文档，（文档在应用程序启动时自动生成，所以不会增加应用程序运行时的开销）。
    * 如果您不使用 FastAPI 而直接使用 Starlette（或诸如 Sanic，Flask，Responder 等其它工具），您则要自己实现所有的数据验证和序列化。那么最终您的应用程序会和使用 FastAPI 构建的程序有相同的开销。一般这种数据验证和序列化的操作在您应用程序的代码中会占很大比重。

# History, Design and Future

Some time ago, <a href="https://github.com/fastapi/fastapi/issues/3#issuecomment-454956920" class="external-link" target="_blank">a **FastAPI** user asked</a>:

> What’s the history of this project? It seems to have come from nowhere to awesome in a few weeks [...]

Here's a little bit of that history.

## Alternatives

# História, Design e Futuro

Há algum tempo, <a href="https://github.com/fastapi/fastapi/issues/3#issuecomment-454956920" class="external-link" target="_blank">um usuário **FastAPI** perguntou</a>:

> Qual é a história desse projeto? Parece que surgiu do nada e se tornou incrível em poucas semanas [...]

Aqui está um pouco dessa história.

## Alternativas

    * Starlette следует сравнивать с Sanic, Flask, Django и другими веб-фреймворками (или микрофреймворками).

* **FastAPI**:
    * Так же как Starlette использует Uvicorn и не может быть быстрее него, **FastAPI** использует Starlette, то есть он не может быть быстрее Starlette.

    * Wenn Sie Starlette vergleichen, vergleichen Sie es mit Webframeworks (oder Mikroframeworks) wie Sanic, Flask, Django, usw.
* **FastAPI**:
    * So wie Starlette Uvicorn verwendet und nicht schneller als dieses sein kann, verwendet **FastAPI** Starlette, sodass es nicht schneller als dieses sein kann.

You can use the `TestClient` class to test FastAPI applications without creating an actual HTTP and socket connection, just communicating directly with the FastAPI code.

Read more about it in the [FastAPI docs for Testing](https://fastapi.tiangolo.com/tutorial/testing/).

You can import it directly from `fastapi.testclient`:

```python
from fastapi.testclient import TestClient
```

## Bibliotecas GraphQL

Aqui estão algumas das bibliotecas **GraphQL** que têm suporte **ASGI**. Você pode usá-las com **FastAPI**:

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

`FastAPI` це клас, який успадковується безпосередньо від `Starlette`.

Ви також можете використовувати всю функціональність <a href="https://www.starlette.io/" class="external-link" target="_blank">Starlette</a> у `FastAPI`.

///

### Крок 2: створюємо екземпляр `FastAPI`

```Python hl_lines="3"
{!../../docs_src/first_steps/tutorial001.py!}
```
Змінна `app` є екземпляром класу `FastAPI`.

Using it in your editor is what really shows you the benefits of FastAPI, seeing how little code you have to write, all the type checks, autocompletion, etc.

---

## Install FastAPI

The first step is to install FastAPI.

Make sure you create a [virtual environment](../virtual-environments.md){.internal-link target=_blank}, activate it, and then **install FastAPI**:

<div class="termy">

```console

from fastapi import FastAPI, Request, status
from fastapi.encoders import jsonable_encoder
from fastapi.exceptions import RequestValidationError
from fastapi.responses import JSONResponse
from pydantic import BaseModel

app = FastAPI()


@app.exception_handler(RequestValidationError)
async def validation_exception_handler(request: Request, exc: RequestValidationError):
    return JSONResponse(
        status_code=status.HTTP_422_UNPROCESSABLE_ENTITY,