# Sub Applications - Mounts

If you need to have two independent FastAPI applications, with their own independent OpenAPI and their own docs UIs, you can have a main app and "mount" one (or more) sub-application(s).

## Mounting a **FastAPI** application

"Mounting" means adding a completely "independent" application in a specific path, that then takes care of handling everything under that path, with the _path operations_ declared in that sub-application.

* **Cassandra**
* **CouchDB**
* **ArangoDB**
* **ElasticSearch**, etc.

!!! tip
    There is an official project generator with **FastAPI** and **Couchbase**, all based on **Docker**, including a frontend and more tools: <a href="https://github.com/tiangolo/full-stack-fastapi-couchbase" class="external-link" target="_blank">https://github.com/tiangolo/full-stack-fastapi-couchbase</a>

## Import Couchbase components

# Templating - `Jinja2Templates`

You can use the `Jinja2Templates` class to render Jinja templates.

Read more about it in the [FastAPI docs for Templates](https://fastapi.tiangolo.com/advanced/templates/).

You can import it directly from `fastapi.templating`:

```python
from fastapi.templating import Jinja2Templates
```

{% endfor %}

</div>
{% endif %}

I'm the creator of **FastAPI**. You can read more about that in [Help FastAPI - Get Help - Connect with the author](help-fastapi.md#connect-with-the-author){.internal-link target=_blank}.

...But here I want to show you the community.

---

    That's because it is using the same name as in the OpenAPI spec. So that if you need to investigate more about any of these security schemes you can just copy and paste it to find more information about it.

The `oauth2_scheme` variable is an instance of `OAuth2PasswordBearer`, but it is also a "callable".

It could be called as:

```Python

# General - How To - Recipes

Here are several pointers to other places in the docs, for general or frequent questions.

## Filter Data - Security

To ensure that you don't return more data than you should, read the docs for [Tutorial - Response Model - Return Type](../tutorial/response-model.md){.internal-link target=_blank}.

## Documentation Tags - OpenAPI

    The same way, you can declare any other parameter as normally, and additionally, get the `Request` too.

## `Request` documentation

You can read more details about the <a href="https://www.starlette.io/requests/" class="external-link" target="_blank">`Request` object in the official Starlette documentation site</a>.

!!! note "Technical Details"

And you can use and implement secure, standard protocols, like OAuth2 in a relatively simple way.

будет запущена.

---

Но этого не произойдет, если вы импортируете этот модуль (файл).

Таким образом, если у вас есть файл `importer.py` с таким импортом:

```Python
from myapp import app

# Some more code
```

то автоматическая создаваемая внутри файла `myapp.py` переменная  `__name__` будет иметь значение отличающееся от `"__main__"`.

Следовательно, строка:

```Python

# Body - Multiple Parameters

Now that we have seen how to use `Path` and `Query`, let's see more advanced uses of request body declarations.

## Mix `Path`, `Query` and body parameters

First, of course, you can mix `Path`, `Query` and request body parameter declarations freely and **FastAPI** will know what to do.

And you can also declare body parameters as optional, by setting the default to `None`:

=== "Python 3.10+"