This might all sound abstract. Don't worry. You'll see all this in action in the [Tutorial - User Guide](tutorial/index.md){.internal-link target=_blank}.

The important thing is that by using standard Python types, in a single place (instead of adding more classes, decorators, etc), **FastAPI** will do a lot of the work for you.

!!! info

## Was ist „Dependency Injection“

**„Dependency Injection“** bedeutet in der Programmierung, dass es für Ihren Code (in diesem Fall Ihre *Pfadoperation-Funktionen*) eine Möglichkeit gibt, Dinge zu deklarieren, die er verwenden möchte und die er zum Funktionieren benötigt: „Abhängigkeiten“ – „Dependencies“.

Username: `johndoe`
Password: `secret`

!!! check
    Notice that nowhere in the code is the plaintext password "`secret`", we only have the hashed version.

<img src="/img/tutorial/security/image08.png">

Call the endpoint `/users/me/`, you will get the response as:

```JSON
{
  "username": "johndoe",
  "email": "******@****.***",
  "full_name": "John Doe",
  "disabled": false
}
```

        self.name = name
        self.call = call
        self.use_cache = use_cache
        # Store the path to be able to re-generate a dependable from it in overrides
        self.path = path
        # Save the cache key at creation to optimize performance

                return await app(scope, receive, send)  # pragma: no cover

            async def call_next():
                return await app(scope, receive, send)

            websocket = WebSocket(scope, receive=receive, send=send)
            return await middleware_func(websocket, call_next)

        return wrapped_app

    return middleware_constructor


def test_depend_validation():

* `/items/`
* `/items/{item_id}`

It's all the same structure as with `app/routers/users.py`.

But we want to be smarter and simplify the code a bit.

We know all the *path operations* in this module have the same:

* Path `prefix`: `/items`.
* `tags`: (just one tag: `items`).
* Extra `responses`.
* `dependencies`: they all need that `X-Token` dependency we created.

Sie können den Typ eines Pfad-Parameters in der Argumentliste der Funktion deklarieren, mit Standard-Python-Typannotationen:

```Python hl_lines="7"
{!../../../docs_src/path_params/tutorial002.py!}
```

In diesem Fall wird `item_id` als `int` deklariert, also als Ganzzahl.

!!! check
    Dadurch erhalten Sie Editor-Unterstützung innerhalb Ihrer Funktion, mit Fehlerprüfungen, Codevervollständigung, usw.

    ```Python hl_lines="15"
    {!> ../../../docs_src/dependencies/tutorial012.py!}
    ```

And all the ideas in the section about [adding `dependencies` to the *path operation decorators*](dependencies-in-path-operation-decorators.md){.internal-link target=_blank} still apply, but in this case, to all of the *path operations* in the app.

## Dependencies for groups of *path operations*

from pydantic import BaseModel, BaseSettings, SecretStr

awaiting_label = "awaiting-review"
lang_all_label = "lang-all"
approved_label = "approved-2"
translations_path = Path(__file__).parent / "translations.yml"

github_graphql_url = "https://api.github.com/graphql"
questions_translations_category_id = "DIC_kwDOCZduT84CT5P9"

all_discussions_query = """
query Q($category_id: ID) {
  repository(name: "fastapi", owner: "tiangolo") {

{% endfor %}

</div>
{% endif %}

### FastAPI Experts - All Time

Here are the all time **FastAPI Experts**. 🤓🤯

These are the users that have [helped others the most with questions in GitHub](help-fastapi.md#help-others-with-questions-in-github){.internal-link target=_blank} through *all time*. 🧙

{% if people %}
<div class="user-list user-list-center">