* Declaración de **parámetros** en otros lugares diferentes cómo los: **headers**, **cookies**, **formularios** y **archivos**.
* Cómo agregar **requisitos de validación** cómo `maximum_length` o `regex`.
* Un sistema de **<abbr title="también conocido en inglés cómo: components, resources, providers, services, injectables">Dependency Injection</abbr>** poderoso y fácil de usar.

                            * `security_scopes.scopes` wird `[]` (nichts) für die *Pfadoperation* `read_system_status` enthalten, da diese keine `Security` mit `scopes` deklariert hat, und deren Abhängigkeit `get_current_user` ebenfalls keinerlei `scopes` deklariert.

!!! tip "Tipp"

<img src="/img/tutorial/query-params-str-validations/image01.png">

## Parameter von OpenAPI ausschließen

Um einen Query-Parameter vom generierten OpenAPI-Schema auszuschließen (und daher von automatischen Dokumentations-Systemen), setzen Sie den Parameter `include_in_schema` in `Query` auf `False`.

=== "Python 3.10+"

    ```Python hl_lines="10"
    {!> ../../../docs_src/query_params_str_validations/tutorial014_an_py310.py!}
    ```

* Any keyword arguments that should be passed to the task function (`message="some notification"`).

## Dependency Injection

Using `BackgroundTasks` also works with the dependency injection system, you can declare a parameter of type `BackgroundTasks` at multiple levels: in a *path operation function*, in a dependency (dependable), in a sub-dependency, etc.

    * All this would also work for deeply nested JSON objects.
* Convert from and to JSON automatically.
* Document everything with OpenAPI, that can be used by:
    * Interactive documentation systems.
    * Automatic client code generation systems, for many languages.
* Provide 2 interactive documentation web interfaces directly.

---

We just scratched the surface, but you already get the idea of how it all works.

### Types and validation

These environment variables can only handle text strings, as they are external to Python and have to be compatible with other programs and the rest of the system (and even with different operating systems, as Linux, Windows, macOS).

That means that any value read in Python from an environment variable will be a `str`, and any conversion to a different type or validation has to be done in code.

* istemci tarafından ağ üzerinden veri göndermek
* ağ üzerinden istemciye gönderilen veriler
* sistem tarafından okunacak ve programınıza verilecek bir dosya içeriği
* programınızın diske yazılmak üzere sisteme verdiği dosya içerikleri
* uzak bir API işlemi
* bir veritabanı bitirme işlemi
* sonuçları döndürmek için bir veritabanı sorgusu
* vb.

# Classes as Dependencies

Before diving deeper into the **Dependency Injection** system, let's upgrade the previous example.

## A `dict` from the previous example

In the previous example, we were returning a `dict` from our dependency ("dependable"):

=== "Python 3.10+"

    ```Python hl_lines="9"
    {!> ../../../docs_src/dependencies/tutorial001_an_py310.py!}
    ```

=== "Python 3.9+"

    ```Python hl_lines="11"

that you can more easily get a good answer, or even solve the problem yourself even before asking. And in GitHub I can make sure I always answer everything, even if it takes some time. I can't personally do that with the chat systems. 😅

Conversations in the chat systems are also not as easily searchable as in GitHub, so questions and answers might get lost in the conversation. And only the ones in GitHub count to become a [FastAPI Expert](fastapi-people.md#fastapi-experts){.internal-link...

Here's a little bit of that history.

## Alternatives

I have been creating APIs with complex requirements for several years (Machine Learning, distributed systems, asynchronous jobs, NoSQL databases, etc), leading several teams of developers.

As part of that, I needed to investigate, test and use many alternatives.