It can't handle nested models very well. So, if the JSON body in the request is a JSON object that has inner fields that in turn are nested JSON objects, it cannot be properly documented and validated.

!!! check "Inspired **FastAPI** to"

Up to here, everything would work as normally.

But then, when you open the integrated docs UI (the frontend), it would expect to get the OpenAPI schema at `/openapi.json`, instead of `/api/v1/openapi.json`.

`response_model` receives the same type you would declare for a Pydantic model field, so, it can be a Pydantic model, but it can also be, e.g. a `list` of Pydantic models, like `List[Item]`.

    * `--reload`: lässt den Server nach Codeänderungen neu starten. Verwenden Sie das nur während der Entwicklung.

In der Konsolenausgabe sollte es eine Zeile geben, die ungefähr so aussieht:

```hl_lines="4"
INFO:     Uvicorn running on http://127.0.0.1:8000 (Press CTRL+C to quit)
```

Diese Zeile zeigt die URL, unter der Ihre Anwendung auf Ihrem lokalen Computer bereitgestellt wird.

```Python
images: List[Image]
```

oder in Python 3.9 und darüber:

```Python
images: list[Image]
```

so wie in:

=== "Python 3.9+"

    ```Python hl_lines="13"
    {!> ../../../docs_src/body_nested_models/tutorial008_py39.py!}
    ```

=== "Python 3.8+"

    ```Python hl_lines="15"

```

...that's because the client generator uses the OpenAPI internal **operation ID** for each *path operation*.

OpenAPI requires that each operation ID is unique across all the *path operations*, so FastAPI uses the **function name**, the **path**, and the **HTTP method/operation** to generate that operation ID, because that way it can make sure that the operation IDs are unique.

But I'll show you how to improve that next. 🤓

This will be the main point of interaction to create all your API.

### Step 3: create a *path operation*

#### Path

"Path" here refers to the last part of the URL starting from the first `/`.

So, in a URL like:

```
https://example.com/items/foo
```

...the path would be:

```
/items/foo
```

!!! info
    A "path" is also commonly called an "endpoint" or a "route".

* 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`.

The domains are securely verified and the certificates are generated automatically. This also allows automating the renewal of these certificates.

The idea is to automate the acquisition and renewal of these certificates so that you can have **secure HTTPS, for free, forever**.

## HTTPS for Developers

    So let's focus on the main cases, where it could crash entirely in some particular cases **in the future**, and it still makes sense to restart it.