## More info { #more-info }

For more info about <abbr title="Cross-Origin Resource Sharing">CORS</abbr>, check the <a href="https://developer.mozilla.org/en-US/docs/Web/HTTP/CORS" class="external-link" target="_blank">Mozilla CORS documentation</a>.

/// note | Technical Details

You could also use `from starlette.middleware.cors import CORSMiddleware`.

/// tip

To know more about each status code and which code is for what, check the <a href="https://developer.mozilla.org/en-US/docs/Web/HTTP/Status" class="external-link" target="_blank"><abbr title="Mozilla Developer Network">MDN</abbr> documentation about HTTP status codes</a>.

///

## Shortcut to remember the names { #shortcut-to-remember-the-names }

If you want to read more about these encodings and form fields, head to the <a href="https://developer.mozilla.org/en-US/docs/Web/HTTP/Methods/POST" class="external-link" target="_blank"><abbr title="Mozilla Developer Network">MDN</abbr> web docs for <code>POST</code></a>.

///

/// warning

If you want to read more about these encodings and form fields, head to the <a href="https://developer.mozilla.org/en-US/docs/Web/HTTP/Methods/POST" class="external-link" target="_blank"><abbr title="Mozilla Developer Network">MDN</abbr> web docs for <code>POST</code></a>.

///

/// warning

The proxy headers are:

* <a href="https://developer.mozilla.org/en-US/docs/Web/HTTP/Reference/Headers/X-Forwarded-For" class="external-link" target="_blank">X-Forwarded-For</a>
* <a href="https://developer.mozilla.org/en-US/docs/Web/HTTP/Reference/Headers/X-Forwarded-Proto" class="external-link" target="_blank">X-Forwarded-Proto</a>

# Body - Updates { #body-updates }

## Update replacing with `PUT` { #update-replacing-with-put }

To update an item you can use the <a href="https://developer.mozilla.org/en-US/docs/Web/HTTP/Methods/PUT" class="external-link" target="_blank">HTTP `PUT`</a> operation.

You can use the `jsonable_encoder` to convert the input data to data that can be stored as JSON (e.g. with a NoSQL database). For example, converting `datetime` to `str`.

///

## Custom Headers { #custom-headers }

Keep in mind that custom proprietary headers can be added <a href="https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers" class="external-link" target="_blank">using the 'X-' prefix</a>.

The proxy headers are:

* <a href="https://developer.mozilla.org/en-US/docs/Web/HTTP/Reference/Headers/X-Forwarded-For" class="external-link" target="_blank">X-Forwarded-For</a>
* <a href="https://developer.mozilla.org/en-US/docs/Web/HTTP/Reference/Headers/X-Forwarded-Proto" class="external-link" target="_blank">X-Forwarded-Proto</a>

* You can then further modify the `response` before returning it.

{* ../../docs_src/middleware/tutorial001.py hl[8:9,11,14] *}

/// tip

Keep in mind that custom proprietary headers can be added <a href="https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers" class="external-link" target="_blank">using the 'X-' prefix</a>.

# WebSockets { #websockets }

You can use <a href="https://developer.mozilla.org/en-US/docs/Web/API/WebSockets_API" class="external-link" target="_blank">WebSockets</a> with **FastAPI**.

## Install `WebSockets` { #install-websockets }

Make sure you create a [virtual environment](../virtual-environments.md){.internal-link target=_blank}, activate it, and install `websockets`:

<div class="termy">

```console
$ pip install websockets

---> 100%