</pre>


<h3 id="Receive_operator">Receive operator</h3>

<p>
For an operand <code>ch</code> of <a href="#Channel_types">channel type</a>,
the value of the receive operation <code>&lt;-ch</code> is the value received
from the channel <code>ch</code>. The channel direction must permit receive operations,
and the type of the receive operation is the element type of the channel.

Let's imagine that you have a database `fake_db` that only receives JSON compatible data.

For example, it doesn't receive `datetime` objects, as those are not compatible with JSON.

So, a `datetime` object would have to be converted to a `str` containing the data in <a href="https://en.wikipedia.org/wiki/ISO_8601" class="external-link" target="_blank">ISO format</a>.

We are still using the same `OAuth2PasswordRequestForm`. It includes a property `scopes` with a `list` of `str`, with each scope it received in the request.

And we return the scopes as part of the JWT token.

/// danger

For simplicity, here we are just adding the scopes received directly to the token.

If a client tries to send some **extra cookies**, they will receive an **error** response.

Poor cookie banners with all their effort to get your consent for the <abbr title="This is another joke. Don't pay attention to me. Have some coffee for your cookie. ☕">API to reject it</abbr>. 🍪

```JSON
{
  "title": "towel",
  "size": "XL"
}
```

You will receive a response telling you that the data is invalid containing the received body:

```JSON hl_lines="12-15"
{
  "detail": [
    {
      "loc": [
        "body",
        "size"
      ],
      "msg": "value is not a valid integer",
      "type": "type_error.integer"
    }
  ],

</pre>


<h3 id="Receive_operator">Receive operator</h3>

<p>
For an operand <code>ch</code> whose <a href="#Core_types">core type</a> is a
<a href="#Channel_types">channel</a>,
the value of the receive operation <code>&lt;-ch</code> is the value received
from the channel <code>ch</code>. The channel direction must permit receive operations,
and the type of the receive operation is the element type of the channel.

    * This way you can update only the values actually set by the user, instead of overriding values already stored with default values in your model.
* Create a copy of the stored model, updating its attributes with the received partial updates (using the `update` parameter).
* Convert the copied model to something that can be stored in your DB (for example, using the `jsonable_encoder`).

///

The `status_code` parameter receives a number with the HTTP status code.

/// info

`status_code` can alternatively also receive an `IntEnum`, such as Python's <a href="https://docs.python.org/3/library/http.html#http.HTTPStatus" class="external-link" target="_blank">`http.HTTPStatus`</a>.

///

///

## 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.
    * This function will pass the `request` to the corresponding *path operation*.
    * Then it returns the `response` generated by the corresponding *path operation*.

Inside of your *path operation function*, pass your task function to the *background tasks* object with the method `.add_task()`:

{* ../../docs_src/background_tasks/tutorial001.py hl[14] *}

`.add_task()` receives as arguments:

* A task function to be run in the background (`write_notification`).
* Any sequence of arguments that should be passed to the task function in order (`email`).