end

    rect rgba(0, 255, 0, .1)
        code ->> function: say_hi(name="Rick")
        function ->> execute: führe Code der Funktion aus
        execute ->> code: gib das Resultat zurück
    end

    rect rgba(0, 255, 0, .1)
        code ->> function: say_hi(name="Rick", salutation="Mr.")
        function ->> execute: führe Code der Funktion aus

```Python
q: Annotated[str, Query(default="rick")] = "morty"
```

...because it's not clear if the default value should be `"rick"` or `"morty"`.

So, you would use (preferably):

```Python
q: Annotated[str, Query()] = "rick"
```

...or in older code bases you will find:

```Python
q: str = Query(default="rick")
```

### Advantages of `Annotated`

!!! tip
    This is just standard Python, it's called a "type alias", it's actually not specific to **FastAPI**.

    But because **FastAPI** is based on the Python standards, including `Annotated`, you can use this trick in your code. 😎

Moitra, Ben Barsdell, Bhavani Subramanian, Boian Petkantchin, BrianWieder, Chris Mc, cloudhan, Connor Flanagan, Daniel Lang, Daniel Yudelevich, Darya Parygina, David Korczynski, David Svantesson, dingyuqing05, Dragan Mladjenovic, dskkato, Eli Kobrin, Erick Ochoa, Erik Schultheis, Frédéric Bastien, gaikwadrahul8, Gauri1 Deshpande, guozhong.zhuang, H. Vetinari, Isaac Cilia Attard, Jake Hall, Jason Furmanek, Jerry Ge, Jinzhe Zeng, JJ, johnnkp, Jonathan Albrecht, jongkweh, justkw, Kanvi Khanna, kikoxia,...

val startScripts = tasks.register<GradleStartScriptGenerator>("startScripts") {
    startScriptsDir = layout.buildDirectory.dir("startScripts")
    launcherJar.from(tasks.jar)
    agentJars.from(agentsClasspath)
    // The trick below is to use the templates from the current code instead of the wrapper. It does not cover the case where the generation logic is updated though.

!!! info
    Keep in mind that dataclasses can't do everything Pydantic models can do.

    So, you might still need to use Pydantic models.

    But if you have a bunch of dataclasses laying around, this is a nice trick to use them to power a web API using FastAPI. 🤓

## Dataclasses in `response_model`

You can also use `dataclasses` in the `response_model` parameter:

```Python hl_lines="1  7-13  19"

    Daher müssen Sie möglicherweise weiterhin Pydantic-Modelle verwenden.

    Wenn Sie jedoch eine Menge Datenklassen herumliegen haben, ist dies ein guter Trick, um sie für eine Web-API mithilfe von FastAPI zu verwenden. 🤓

## Datenklassen als `response_model`

Sie können `dataclasses` auch im Parameter `response_model` verwenden:

```Python hl_lines="1  7-13  19"

    end

    rect rgba(0, 255, 0, .1)
        code ->> function: say_hi(name="Rick")
        function ->> execute: execute function code
        execute ->> code: return the result
    end

    rect rgba(0, 255, 0, .1)
        code ->> function: say_hi(name="Rick", salutation="Mr.")
        function ->> execute: execute function code
        execute ->> code: return the result
    end

```Python
q: Annotated[str, Query(default="rick")] = "morty"
```

...потому что нельзя однозначно определить, что именно должно быть значением по умолчанию: `"rick"` или `"morty"`.

Вам следует использовать (предпочтительно):

```Python
q: Annotated[str, Query()] = "rick"
```

...или как в старом коде, который вам может попасться:

```Python
q: str = Query(default="rick")
```

```Python
q: Annotated[str, Query(default="rick")] = "morty"
```

... denn es wird nicht klar, ob der Defaultwert `"rick"` oder `"morty"` sein soll.

Sie würden also (bevorzugt) schreiben:

```Python
q: Annotated[str, Query()] = "rick"
```

In älterem Code werden Sie auch finden:

```Python
q: str = Query(default="rick")
```

### Vorzüge von `Annotated`