## Requisitos

FastAPI está sobre los hombros de gigantes:

* <a href="https://www.starlette.io/" class="external-link" target="_blank">Starlette</a> para las partes web.
* <a href="https://docs.pydantic.dev/" class="external-link" target="_blank">Pydantic</a> para las partes de datos.

## Instalación

<div class="termy">

```console
$ pip install fastapi

---> 100%
```

</div>

### The callback path expression

The callback *path* can have an <a href="https://github.com/OAI/OpenAPI-Specification/blob/master/versions/3.1.0.md#key-expression" class="external-link" target="_blank">OpenAPI 3 expression</a> that can contain parts of the original request sent to *your API*.

In this case, it's the `str`:

```Python
q: Union[str, None] = None
```

Mas o declara explicitamente como um parâmetro de consulta.

/// info | "Informação"

Tenha em mente que o FastAPI se preocupa com a parte:

```Python
= None
```

Ou com:

```Python
= Query(default=None)
```

E irá utilizar o `None` para detectar que o parâmetro de consulta não é obrigatório.

{!../../docs_src/app_testing/test_main.py!}
```

...e ter o código para os testes como antes.

## Testando: exemplo estendido

Agora vamos estender este exemplo e adicionar mais detalhes para ver como testar diferentes partes.

### Arquivo de aplicativo **FastAPI** estendido

Vamos continuar com a mesma estrutura de arquivo de antes:

```
.
├── app
│   ├── __init__.py
│   ├── main.py
│   └── test_main.py
```

```

You may run builds and tests against different versions of Python sequentially
on the same machine by simply switching the value of `HERMETIC_PYTHON_VERSION`
between the runs. All the python-agnostic parts of the build cache from the
previous build will be preserved and reused for the subsequent builds.

### Specifying Python dependencies

During bazel build all TensorFlow's Python dependencies are pinned to their

Dans ce cadre, j'ai dû étudier, tester et utiliser de nombreuses alternatives.

L'histoire de **FastAPI** est en grande partie l'histoire de ses prédécesseurs.

Comme dit dans la section [Alternatives](alternatives.md){.internal-link target=\_blank} :

<blockquote markdown="1">

**FastAPI** n'existerait pas sans le travail antérieur d'autres personnes.

	// version that created this version of the object.
	WrittenByVersion uint64 `msg:"wv"`

	// File metadata
	Metadata map[string]string `msg:"meta"`

	// All the parts per object.
	Parts []ObjectPartInfo `msg:"parts"`

	// Erasure info for all objects.
	Erasure ErasureInfo `msg:"ei"`

	MarkDeleted      bool             `msg:"md"` // mark this version as deleted

type float64 float64

// complex64 is the set of all complex numbers with float32 real and
// imaginary parts.
type complex64 complex64

// complex128 is the set of all complex numbers with float64 real and
// imaginary parts.
type complex128 complex128

// string is the set of all strings of 8-bit bytes, conventionally but not

    val size: Int = multipartBody.size()
    val parts: List<MultipartBody.Part> = multipartBody.parts()
  }

  @Test @Disabled
  fun multipartBodyPart() {
    val multipartBody: MultipartBody = MultipartBody.Builder().build()
    val part: MultipartBody.Part = multipartBody.part(0)
    val headers: Headers? = part.headers()
    val body: RequestBody = part.body()
  }

  @Test @Disabled
  fun okHttpClient() {

## In a hurry?

<abbr title="too long; didn't read"><strong>TL;DR:</strong></abbr>

If you are using third party libraries that tell you to call them with `await`, like:

```Python
results = await some_library()
```

Then, declare your *path operation functions* with `async def` like:

```Python hl_lines="2"
@app.get('/')