</mxGeometry>
                </mxCell>
                <mxCell id="33" value="" style="group" parent="1" vertex="1" connectable="0">
                    <mxGeometry x="-140" y="-75" width="500" height="350" as="geometry"/>
                </mxCell>

This works the same way as with Pydantic models. And it is actually achieved in the same way underneath, using Pydantic.

!!! 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`

If something seems interesting and useful to your project, go ahead and check it, but otherwise, you might probably just skip them.

!!! tip

    ```

Notice that we declare the type of `current_user` as the Pydantic model `User`.

This will help us inside of the function with all the completion and type checks.

!!! tip
    You might remember that request bodies are also declared with Pydantic models.

    Here **FastAPI** won't get confused because you are using `Depends`.

!!! check

You can create production applications with **FastAPI** right now (and you have probably been doing it for some time), you just have to make sure that you use a version that works correctly with the rest of your code.

## Pin your `fastapi` version

Depending on your use case, you might prefer to use a different library, but if you asked me, I would probably suggest you try **Strawberry**.

Here's a small preview of how you could integrate Strawberry with FastAPI:

```Python hl_lines="3  22  25-26"

## Separating tests

In a real application, you probably would have your tests in a different file.

And your **FastAPI** application might also be composed of several files/modules, etc.

### **FastAPI** app file

Let's say you have a file structure as described in [Bigger Applications](bigger-applications.md){.internal-link target=_blank}:

```
.

                    <mxGeometry x="130" y="565" width="370" height="100" as="geometry"/>
                </mxCell>
                <mxCell id="5" value="" style="rounded=0;whiteSpace=wrap;html=1;fontStyle=1;strokeWidth=4;" parent="1" vertex="1">
                    <mxGeometry x="1030" y="430" width="400" height="260" as="geometry"/>
                </mxCell>

# FastAPI und Freunde Newsletter

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Or it might be the case that you just prefer to take other courses because they adapt better to your learning style.