* Path operasyonu parametreleri içerisinde belirtilen gereksinimler için bile **Otomatik doğrulama** yapılabiliyor.
* Kompleks kimlik doğrulama sistemleri için destek, **database bağlantıları**, vs.
* **Taviz yok** hiçbir şeyden taviz vermeden, database frontend vs. Bütün hepsinin kolayca entegre edilebiliyor.

### Sınırsız "plug-inler"

### Multiple Applications

In the same server (or servers), there could be **multiple applications**, for example, other API programs or a database.

    * Converte i tipi di Python (`str`, `int`, `float`, `bool`, `list`, ecc).
    * Oggetti `datetime`.
    * Oggetti `UUID`.
    * Modelli del database.
    * ...e molto di più.
* Generazione di una documentazione dell'API interattiva, con scelta dell'interfaccia grafica:
    * Swagger UI.
    * ReDoc.

---

Tornando al precedente esempio, **FastAPI**:

And the spec says that the fields have to be named like that. So `user-name` or `email` wouldn't work.

But don't worry, you can show it as you wish to your final users in the frontend.

And your database models can use any other names you want.

But for the login *path operation*, we need to use these names to be compatible with the spec (and be able to, for example, use the integrated API documentation system).

!!! note
    You can only use `await` inside of functions created with `async def`.

---

If you are using a third party library that communicates with something (a database, an API, the file system, etc.) and doesn't have support for using `await`, (this is currently the case for most database libraries), then declare your *path operation functions* as normally, with just `def`, like:

```Python hl_lines="2"
@app.get('/')
def results():

You will see examples of this in the next chapters, about relational and NoSQL databases, security, etc.

## **FastAPI** compatibility

The simplicity of the dependency injection system makes **FastAPI** compatible with:

* all the relational databases
* NoSQL databases
* external packages
* external APIs
* authentication and authorization systems
* API usage monitoring systems

That way, in many cases you can learn about containers and Docker and re-use that knowledge with many different tools and components.

# Settings and Environment Variables

In many cases your application could need some external settings or configurations, for example secret keys, database credentials, credentials for email services, etc.

Most of these settings are variable (can change), like database URLs. And many could be sensitive, like secrets.

For this reason it's common to provide them in environment variables that are read by the application.

## Environment Variables

!!! tip

    author_link: https://www.linkedin.com/in/adejumoridwan/
    link: https://medium.com/python-in-plain-english/build-an-sms-spam-classifier-serverless-database-with-faunadb-and-fastapi-23dbb275bc5b
    title: Build an SMS Spam Classifier Serverless Database with FaunaDB and FastAPI
  - author: Raf Rasenberg
    author_link: https://rafrasenberg.com/about/
    link: https://rafrasenberg.com/fastapi-lambda/

    This is used internally by FastAPI to make sure anything you return can be
    encoded as JSON before it is sent to the client.

    You can also use it yourself, for example to convert objects before saving them
    in a database that supports only JSON.

    Read more about it in the
    [FastAPI docs for JSON Compatible Encoder](https://fastapi.tiangolo.com/tutorial/encoder/).
    """
    custom_encoder = custom_encoder or {}