# About FastAPI versions

**FastAPI** is already being used in production in many applications and systems. And the test coverage is kept at 100%. But its development is still moving quickly.

New features are added frequently, bugs are fixed regularly, and the code is still continuously improving.

# Get Current User

In the previous chapter the security system (which is based on the dependency injection system) was giving the *path operation function* a `token` as a `str`:

=== "Python 3.9+"

    ```Python hl_lines="12"
    {!> ../../../docs_src/security/tutorial001_an_py39.py!}
    ```

=== "Python 3.8+"

    ```Python hl_lines="11"
    {!> ../../../docs_src/security/tutorial001_an.py!}
    ```

=== "Python 3.8+ non-Annotated"

    * If you are comparing Uvicorn, compare it against Daphne, Hypercorn, uWSGI, etc. Application servers.
* **Starlette**:
    * Will have the next best performance, after Uvicorn. In fact, Starlette uses Uvicorn to run. So, it probably can only get "slower" than Uvicorn by having to execute more code.

    }

    loadLines() {
        // Load all the lines and create the container so that the size is fixed
        // Otherwise it would be changing and the user viewport would be constantly
        // moving as she/he scrolls
        const finish = this.generateFinish()
        finish.style.visibility = 'hidden'
        this.container.appendChild(finish)
        // Appends dynamically loaded lines to existing line elements.

    * Lire d'autres idées, articles, et sur les outils que j'ai créés.
    * Suivez-moi pour lire quand je publie quelque chose de nouveau.

## Tweeter sur **FastAPI**

<a href="https://twitter.com/compose/tweet?text=I'm loving FastAPI because... https://github.com/tiangolo/fastapi cc @tiangolo" class="external-link" target="_blank">Tweetez à propos de **FastAPI**</a> et faites-moi savoir, ainsi qu'aux autres, pourquoi vous aimez ça. 🎉

# Advanced Dependencies

## Parameterized dependencies

All the dependencies we have seen are a fixed function or class.

But there could be cases where you want to be able to set parameters on the dependency, without having to declare many different functions or classes.

Let's imagine that we want to have a dependency that checks if the query parameter `q` contains some fixed content.

But we want to be able to parameterize that fixed content.

    * 阅读我的其它想法、文章，了解我创建的工具
    * 关注我，这样就可以随时看到我发布的新文章

## Tweet about **FastAPI**

<a href="https://twitter.com/compose/tweet?text=I'm loving @fastapi because... https://github.com/tiangolo/fastapi" class="external-link" target="_blank">Tweet about **FastAPI**</a> 让我和大家知道您为什么喜欢 FastAPI。🎉

知道有人使用 **FastAPI**，我会很开心，我也想知道您为什么喜欢 FastAPI，以及您在什么项目/哪些公司使用 FastAPI，等等。

As query parameters are not a fixed part of a path, they can be optional and can have default values.

In the example above they have default values of `skip=0` and `limit=10`.

So, going to the URL:

```
http://127.0.0.1:8000/items/
```

would be the same as going to:

```
http://127.0.0.1:8000/items/?skip=0&limit=10
```

But if you go to, for example:

```
http://127.0.0.1:8000/items/?skip=20
```

You will get completion in code you might even consider impossible before. As for example, the `price` key inside a JSON body (that could have been nested) that comes from a request.

No more typing the wrong key names, coming back and forth between docs, or scrolling up and down to find if you finally used `username` or `user_name`.

### Short

But you can still document it as described in [Additional Responses in OpenAPI](additional-responses.md){.internal-link target=_blank}.