You put it on top of a function. Like a pretty decorative hat (I guess that's where the term came from).

A "decorator" takes the function below and does something with it.

In our case, this decorator tells **FastAPI** that the function below corresponds to the **path** `/` with an **operation** `get`.

It is the "**path operation decorator**".

///

You can also use the other operations:

* `@app.post()`

The *path operation decorator* receives an optional argument `dependencies`.

It should be a `list` of `Depends()`:

{* ../../docs_src/dependencies/tutorial006_an_py39.py hl[19] *}

These dependencies will be executed/solved the same way as normal dependencies. But their value (if they return any) won't be passed to your *path operation function*.

/// tip

Lo pones encima de una función. Como un bonito sombrero decorativo (supongo que de ahí viene el término).

Un "decorador" toma la función de abajo y hace algo con ella.

En nuestro caso, este decorador le dice a **FastAPI** que la función de abajo corresponde al **path** `/` con una **operation** `get`.

Es el "**path operation decorator**".

///

También puedes usar las otras operaciones:

* `@app.post()`
* `@app.put()`

Pero también puedes declarar el `Response` que quieres usar (por ejemplo, cualquier subclase de `Response`), en el *path operation decorator* usando el parámetro `response_class`.

Los contenidos que devuelvas desde tu *path operation function* se colocarán dentro de esa `Response`.

# Path Operation Configuration { #path-operation-configuration }

There are several parameters that you can pass to your *path operation decorator* to configure it.

/// warning

Notice that these parameters are passed directly to the *path operation decorator*, not to your *path operation function*.

///

## Response Status Code { #response-status-code }

You can define the (HTTP) `status_code` to be used in the response of your *path operation*.

///

## Create a middleware { #create-a-middleware }

To create a middleware you use the decorator `@app.middleware("http")` on top of a function.

The middleware function receives:

* The `request`.
* A function `call_next` that will receive the `request` as a parameter.

# Configuración de Path Operation

Hay varios parámetros que puedes pasar a tu *path operation decorator* para configurarlo.

/// warning | Advertencia

Ten en cuenta que estos parámetros se pasan directamente al *path operation decorator*, no a tu *path operation function*.

///

## Código de Estado del Response

Puedes definir el `status_code` (HTTP) que se utilizará en el response de tu *path operation*.

import java.io.Serializable;

/**
 * An abstract base class for implementing the <a
 * href="http://en.wikipedia.org/wiki/Decorator_pattern">decorator pattern</a>. The {@link
 * #delegate()} method must be overridden to return the instance being decorated.
 *
 * <p>This class does <i>not</i> forward the {@code hashCode} and {@code equals} methods through to

In those cases, you can use the *path operation decorator* parameter `response_model` instead of the return type.

You can use the `response_model` parameter in any of the *path operations*:

* `@app.get()`
* `@app.post()`
* `@app.put()`
* `@app.delete()`
* etc.

 * service. Subclasses should override one or more methods to modify the behavior of the backing
 * executor service as desired per the <a
 * href="http://en.wikipedia.org/wiki/Decorator_pattern">decorator pattern</a>.
 *
 * <p><b>{@code default} method warning:</b> This class does <i>not</i> forward calls to {@code
 * default} methods. Instead, it inherits their default implementations. When those implementations