///

## Adicione informações extras

Você pode declarar informação extra em `Field`, `Query`, `Body`, etc. E isso será incluído no JSON Schema gerado.

Você irá aprender mais sobre adicionar informações extras posteriormente nessa documentação, quando estiver aprendendo a declarar exemplos.

## Recapitulando

Você pode usar `Field` do Pydantic para declarar validações extras e metadados para atributos do modelo.

   *
   * @return this method does not return; it always throws
   * @throws IOException when the given throwable is an IOException
   * @throws X1 when the given throwable is of the declared type X1
   * @throws X2 when the given throwable is of the declared type X2
   */
  public <X1 extends Exception, X2 extends Exception> RuntimeException rethrow(
      Throwable e, Class<X1> declaredType1, Class<X2> declaredType2) throws IOException, X1, X2 {

```Python hl_lines="31"
{!> ../../docs_src/security/tutorial002.py!}
```

////

Notice that we declare the type of `current_user` as the Pydantic model `User`.

This will help us inside of the function with all the completion and type checks.

/// tip

You might remember that request bodies are also declared with Pydantic models.

Here **FastAPI** won't get confused because you are using `Depends`.

///

Note that in this case, we are declaring a path parameter beside the request parameter.

So, the path parameter will be extracted, validated, converted to the specified type and annotated with OpenAPI.

The same way, you can declare any other parameter as normally, and additionally, get the `Request` too.

///

## `Request` documentation

To use, first add this library as a test dependency:

```
testImplementation("com.squareup.okhttp3:mockwebserver3-junit4:4.12.0")
```

Then in tests annotated `@org.junit.Test`, you may declare a field with the `@Rule` annotation:

```
@Rule public final MockWebServerRule serverRule = new MockWebServerRule();
```

The `serverRule` field has a `server` field. It is an instance of `MockWebServer`. That instance

 * @param <O> The specific Options type this request carries
 *
 * @since 4.0.0
 */
@Experimental
public interface MavenInvokerRequest<O extends MavenOptions> extends InvokerRequest<O> {
    // This interface doesn't declare any additional methods beyond those inherited from InvokerRequest.
    // It serves to type-specify the Options as MavenOptions for Maven-specific requests.

```Python hl_lines="1  3" title="app/routers/users.py"
{!../../docs_src/bigger_applications/app/routers/users.py!}
```

### *Path operations* with `APIRouter`

And then you use it to declare your *path operations*.

Use it the same way you would use the `FastAPI` class:

```Python hl_lines="6  11  16" title="app/routers/users.py"
{!../../docs_src/bigger_applications/app/routers/users.py!}
```

# WebSockets

When defining WebSockets, you normally declare a parameter of type `WebSocket` and with it you can read data from the client and send data to it.

It is provided directly by Starlette, but you can import it from `fastapi`:

```python
from fastapi import WebSocket
```

/// tip

We can do better...

## What makes a dependency

Up to now you have seen dependencies declared as functions.

But that's not the only way to declare dependencies (although it would probably be the more common).

The key factor is that a dependency should be a "callable".

///

## Dependencies errors and return values

You can use the same dependency *functions* you use normally.

### Dependency requirements

They can declare request requirements (like headers) or other sub-dependencies:

//// tab | Python 3.9+

```Python hl_lines="8  13"
{!> ../../docs_src/dependencies/tutorial006_an_py39.py!}
```

////

//// tab | Python 3.8+