Erstellen Sie dann Klassen-Attribute mit festgelegten Werten, welches die erlaubten Werte sein werden:

```Python hl_lines="1  6-9"
{!../../docs_src/path_params/tutorial005.py!}
```

/// info

<a href="https://docs.python.org/3/library/enum.html" class="external-link" target="_blank">Enumerationen (oder kurz Enums)</a> gibt es in Python seit Version 3.4.

///

/// tip | "Tipp"

### Virtuelle Umgebung mit `venv`

Sie können mit dem Python-Modul `venv` in einem Verzeichnis eine isolierte virtuelle lokale Umgebung erstellen. Machen wir das im geklonten Repository (da wo sich die `requirements.txt` befindet):

<div class="termy">

```console
$ python -m venv env
```

</div>

//// tab | Python 3.10+

```Python hl_lines="8-9"
{!> ../../docs_src/dependencies/tutorial001_an_py310.py!}
```

////

//// tab | Python 3.9+

```Python hl_lines="8-11"
{!> ../../docs_src/dependencies/tutorial001_an_py39.py!}
```

////

//// tab | Python 3.8+

```Python hl_lines="9-12"
{!> ../../docs_src/dependencies/tutorial001_an.py!}
```

它们的工作方式与其他 FastAPI 端点/ *路径操作* 相同：

//// tab | Python 3.10+

```Python hl_lines="68-69  82"
{!> ../../docs_src/websockets/tutorial002_an_py310.py!}
```

////

//// tab | Python 3.9+

```Python hl_lines="68-69  82"
{!> ../../docs_src/websockets/tutorial002_an_py39.py!}
```

////

//// tab | Python 3.8+

```Python hl_lines="69-70  83"

# pylint: disable=g-bad-import-order,protected-access,g-import-not-at-top
from tensorflow.python import pywrap_tensorflow  # pylint: disable=unused-import
from tensorflow.python.tools import module_util as _module_util
from tensorflow.python.platform import tf_logging as _logging
from tensorflow.python.util.lazy_loader import LazyLoader as _LazyLoader
from tensorflow.python.util.lazy_loader import KerasLazyLoader as _KerasLazyLoader

# API IMPORTS PLACEHOLDER

//// tab | Python 3.10+

В Python 3.9 или выше, `Annotated` является частью стандартной библиотеки, таким образом вы можете импортировать его из `typing`.

```Python hl_lines="1  3"
{!> ../../docs_src/query_params_str_validations/tutorial002_an_py310.py!}
```

////

//// tab | Python 3.8+

//// tab | Python 3.10+ Pydantic v2

```Python hl_lines="13-24"
{!> ../../docs_src/schema_extra_example/tutorial001_py310.py!}
```

////

//// tab | Python 3.10+ Pydantic v1

```Python hl_lines="13-23"
{!> ../../docs_src/schema_extra_example/tutorial001_py310_pv1.py!}
```

////

//// tab | Python 3.8+ Pydantic v2

```Python hl_lines="15-26"

* `Annotated` von `typing` (oder von `typing_extensions` in Python unter 3.9)

//// tab | Python 3.10+

In Python 3.9 oder darüber, ist `Annotated` Teil der Standardbibliothek, also können Sie es von `typing` importieren.

```Python hl_lines="1  3"
{!> ../../docs_src/query_params_str_validations/tutorial002_an_py310.py!}
```

////

//// tab | Python 3.8+

In Versionen unter Python 3.9 importieren Sie `Annotated` von `typing_extensions`.

### Apenas Python moderno

Tudo é baseado no padrão das declarações de **tipos do Python 3.8** (graças ao Pydantic). Nenhuma sintaxe nova para aprender. Apenas o padrão moderno do Python.

Se você precisa refrescar a memória rapidamente sobre como usar tipos do Python (mesmo que você não use o FastAPI), confira esse rápido tutorial: [Tipos do Python](python-types.md){.internal-link target=_blank}.

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

⚖️ 🐍 3️⃣.9️⃣ & 🔛:

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

:

//// tab | 🐍 3️⃣.6️⃣ & 🔛

```Python hl_lines="15"
{!> ../../docs_src/body_nested_models/tutorial008.py!}
```

////

//// tab | 🐍 3️⃣.9️⃣ & 🔛

```Python hl_lines="13"