case "${VERSION}" in
devtoolset-7)
mv "/${TARGET}/usr/lib/libstdc++.so.${LIBSTDCXX_VERSION}" \
   "/${TARGET}/usr/lib/libstdc++.so.${LIBSTDCXX_VERSION}.backup"
echo -e "OUTPUT_FORMAT(elf64-x86-64)\nINPUT ( libstdc++.so.6.0.13 -lstdc++_nonshared44 )" \
   > "/${TARGET}/usr/lib/libstdc++.so.${LIBSTDCXX_VERSION}"
cp "./x86_64-pc-linux-gnu/libstdc++-v3/src/.libs/libstdc++_nonshared44.a" \

* There's a subdirectory `app/routers/` with another file `__init__.py`, so it's a "Python subpackage": `app.routers`.
* The file `app/routers/items.py` is inside a package, `app/routers/`, so, it's a submodule: `app.routers.items`.
* The same with `app/routers/users.py`, it's another submodule: `app.routers.users`.
* There's also a subdirectory `app/internal/` with another file `__init__.py`, so it's another "Python subpackage": `app.internal`.

    * So, by using FastAPI you are saving development time, bugs, lines of code, and you would probably get the same performance (or better) you would...

/// tip

This section is useful only to a handful of people, team members with permissions to manage the repository. You can probably skip it. 😉

///

...so, you are a [team member of FastAPI](./fastapi-people.md#team){.internal-link target=_blank}? Wow, you are so cool! 😎

* Und viele andere Dinge ...

All dies, während Sie Codeverdoppelung minimieren.

## Erste Schritte { #first-steps }

Sehen wir uns ein sehr einfaches Beispiel an. Es ist so einfach, dass es vorerst nicht sehr nützlich ist.

Aber so können wir uns besser auf die Funktionsweise des **Dependency Injection** Systems konzentrieren.

The `password` "flow" is one of the ways ("flows") defined in OAuth2, to handle security and authentication.

OAuth2 was designed so that the backend or API could be independent of the server that authenticates the user.

But in this case, the same **FastAPI** application will handle the API and the authentication.

So, let's review it from that simplified point of view:

* The user types the `username` and `password` in the frontend, and hits `Enter`.

Then with `random.choice()` we can get a **random value** from the list, so, we get a tuple with `(id, name)`. It will be something like `("imdb-tt0371724", "The Hitchhiker's Guide to the Galaxy")`.

Then we **assign those two values** of the tuple to the variables `id` and `name`.

So, if the user didn't provide an item ID, they will still receive a random suggestion.

That when called, return instances of classes of the same name.

So, you import `Query`, which is a function. And when you call it, it returns an instance of a class also named `Query`.

These functions are there (instead of just using the classes directly) so that your editor doesn't mark errors about their types.

The same models are shared among requests, so, it's not one model per request, or one per user or something similar.

Let's imagine that loading the model can **take quite some time**, because it has to read a lot of **data from disk**. So you don't want to do it for every request.

We want to get the `current_user` *only* if this user is active.

So, we create an additional dependency `get_current_active_user` that in turn uses `get_current_user` as a dependency.

Both of these dependencies will just return an HTTP error if the user doesn't exist, or if is inactive.

So, in our endpoint, we will only get a user if the user exists, was correctly authenticated, and is active: