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

### *Path operations* with `APIRouter` { #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!}
```

Esse código declara um parâmetro de consulta opcional, `q`, com o tipo `str`, e então retorna esse parâmetro.

Isso é bastante simples (e não muito útil), mas irá nos ajudar a focar em como as subdependências funcionam.

## Segunda dependência, "injetável" e "dependente"

# Security Tools

When you need to declare dependencies with OAuth2 scopes you use `Security()`.

But you still need to define what is the dependable, the callable that you pass as a parameter to `Depends()` or `Security()`.

There are multiple tools that you can use to create those dependables, and they get integrated into OpenAPI so they are shown in the automatic docs UI, they can be used by automatically generated clients and SDKs, etc.

package com.google.common.util.concurrent;

import com.google.common.annotations.GwtCompatible;
import com.google.common.annotations.J2ktIncompatible;

/**
 * Hidden superclass of {@link Futures} that provides us a place to declare special GWT versions of
 * the {@link Futures#catching(ListenableFuture, Class, com.google.common.base.Function,
 * java.util.concurrent.Executor) Futures.catching} family of methods. Those versions have slightly

       execution it sees that the classpath has changed, and so to be
       safe, it needs to re-run.

       - This is unfortunate, because actually it would be safe to declare
       the task as up-to-date, because these two files, which are based on
       the generated index.xml, are outputs, not inputs. We can be sure of
       this because they are deleted in the @BeforeEach method of the

package com.google.common.util.concurrent;

import com.google.common.annotations.GwtCompatible;
import com.google.common.annotations.J2ktIncompatible;

/**
 * Hidden superclass of {@link Futures} that provides us a place to declare special GWT versions of
 * the {@link Futures#catching(ListenableFuture, Class, com.google.common.base.Function,
 * java.util.concurrent.Executor) Futures.catching} family of methods. Those versions have slightly

erations }

Later, when reading about how to structure bigger applications ([Bigger Applications - Multiple Files](../../tutorial/bigger-applications.md){.internal-link target=_blank}), possibly with multiple files, you will learn how to declare a single `dependencies` parameter for a group of *path operations*....

# 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

/**
 * Runtime exception wrapper for ServletException.
 *
 * This exception is used to wrap checked ServletExceptions and convert them
 * into unchecked RuntimeExceptions, allowing them to be thrown from methods
 * that don't declare ServletException in their throws clause.
 */
public class ServletRuntimeException extends RuntimeException {

    /** Serial version UID for serialization compatibility. */
    private static final long serialVersionUID = 1L;

import com.google.common.base.Function;
import java.util.concurrent.Executor;
import org.jspecify.annotations.Nullable;

/**
 * Hidden superclass of {@link FluentFuture} that provides us a place to declare special GWT
 * versions of the {@link FluentFuture#catching(Class, com.google.common.base.Function)
 * FluentFuture.catching} family of methods. Those versions have slightly different signatures.
 */