Notice that the default value is still `None`, so the parameter is still optional.

But now, having `Query(max_length=50)` inside of `Annotated`, we are telling FastAPI that we want it to have **additional validation** for this value, we want it to have maximum 50 characters. 😎

/// tip

If something seems interesting and useful to your project, go ahead and check it, but otherwise, you might probably just skip them.

/// tip

If you want to **learn FastAPI** in a structured way (recommended), go and read the [Tutorial - User Guide](../tutorial/index.md) chapter by chapter instead.

labels.wizard_button_finish=Skip
labels.search_list_configuration=Search
labels.search_list_button_delete=Delete
labels.search_list_delete_confirmation=Are you sure you want to delete?
labels.search_list_button_delete_all=Delete All by this Query
labels.search_list_delete_all_confirmation=Are you sure you want to delete all by this query?
labels.search_list_button_cancel=Cancel
labels.failure_url_configuration=Failure URL
labels.failure_url_search_url=URL

```python
from fastapi import Depends
```

::: fastapi.Depends

## `Security()`

For many scenarios, you can handle security (authorization, authentication, etc.) with dependencies, using `Depends()`.

But when you want to also declare OAuth2 scopes, you can use `Security()` instead of `Depends()`.

You can import `Security()` directly from `fastapi`:

```python
from fastapi import Security
```

              <testTimeOut>86400 <!-- seconds --></testTimeOut>
              <testMethodTimeout>1440 <!-- minutes --></testMethodTimeout>
              <!-- Presumably we want watchFileChanges=false here, since we want it for compile: -->
              <extraJvmArgs>-Dgwt.watchFileChanges=false</extraJvmArgs>
            </configuration>
          </execution>
        </executions>
      </plugin>

# Files that should be ignored by tools which do not want to consider generated
# code.
#
# https://github.com/kubernetes/test-infra/blob/master/prow/plugins/size/size.go
#
# This file is a series of lines, each of the form:
#     <type> <name>
#
# Type can be:
#    path - an exact path to a single file
#    file-name - an exact leaf filename, regardless of path
#    path-prefix - a prefix match on the file path

///

## Use Cases { #use-cases }

You could use this to stream data from an **AI LLM** service, from **logs** or **telemetry**, or from other types of data that can be structured in **JSON** items.

/// tip

If you want to stream binary data, for example video or audio, check the advanced guide: [Stream Data](../advanced/stream-data.md).

///

## Stream JSON Lines with FastAPI { #stream-json-lines-with-fastapi }

Later, for your production application, you might want to use a database server like **PostgreSQL**.

/// tip

There is an official project generator with **FastAPI** and **PostgreSQL** including a frontend and more tools: [https://github.com/fastapi/full-stack-fastapi-template](https://github.com/fastapi/full-stack-fastapi-template)

///

    a documentation issue (for small doc fixes please send a PR instead).
1.  Make sure the Issue Template is filled out.
1.  The issue should be related to the repo it is created in.

**Here's why we have this policy:** We want to focus on the work that benefits
the whole community, e.g., fixing bugs and adding features. Individual support
should be sought on Stack Overflow or other non-GitHub channels. It helps us to

        return 0;
    }

    /*
     * We overload this method from ServerMessageBlock because
     * we want writeAndXWireFormat to write the parameterWords
     * and bytes. This is so we can write batched smbs because
     * all but the first smb of the chaain do not have a header
     * and therefore we do not want to writeHeaderWireFormat. We
     * just recursivly call writeAndXWireFormat.
     */

    @Override