You can override these exception handlers with your own.

### Override request validation exceptions

When a request contains invalid data, **FastAPI** internally raises a `RequestValidationError`.

And it also includes a default exception handler for it.

Then you can write a template at `templates/item.html` with, for example:

```jinja hl_lines="7"
{!../../../docs_src/templates/templates/item.html!}
```

### Template Context Values

In the HTML that contains:

{% raw %}

```jinja
Item ID: {{ id }}
```

{% endraw %}

...it will show the `id` taken from the "context" `dict` you passed:

```Python
{"id": id}
```

### Model for Output Response Data

If you interact with the docs and check the response, even though the code didn't add anything in one of the `description` fields, the JSON response contains the default value (`null`):

<div class="screenshot">
<img src="/img/tutorial/separate-openapi-schemas/image02.png">
</div>