│   └── routers          # „routers“ ist ein „Python-Subpackage“
│   │   ├── __init__.py  # macht „routers“ zu einem „Python-Subpackage“
│   │   ├── items.py     # „items“-Submodul, z. B. import app.routers.items
│   │   └── users.py     # „users“-Submodul, z. B. import app.routers.users
│   └── internal         # „internal“ ist ein „Python-Subpackage“
│       ├── __init__.py  # macht „internal“ zu einem „Python-Subpackage“

```

然後再在其他目錄中查找。

因此，當你在終端機中輸入 `python` 時，系統會在以下目錄中找到 Python 程式：

```plaintext
C:\Users\user\code\awesome-project\.venv\Scripts\python
```

並使用這個。

////

一個重要的細節是，虛擬環境路徑會被放在 `PATH` 變數的**開頭**。系統會在找到任何其他可用的 Python **之前**找到它。這樣，當你運行 `python` 時，它會使用**虛擬環境中的** Python，而不是任何其他 `python`（例如，全域環境中的 `python`）。

啟用虛擬環境還會改變其他一些內容，但這是它所做的最重要的事情之一。

## 檢查虛擬環境

<div class="termy">

```console
$ python myapp.py
```

</div>

but is not called when another file imports it, like in:

```Python
from myapp import app
```

#### More details { #more-details }

Let's say your file is named `myapp.py`.

If you run it with:

<div class="termy">

```console
$ python myapp.py
```

</div>

<div class="termy">

```console
$ python myapp.py
```

</div>

mas não é chamado quando outro arquivo o importa, como em:

```Python
from myapp import app
```

#### Mais detalhes

Digamos que seu arquivo se chama `myapp.py`.

Se você executá-lo com:

<div class="termy">

```console
$ python myapp.py
```

</div>

### Faite en python moderne

Tout est basé sur la déclaration de type standard de **Python 3.8** (grâce à Pydantic). Pas de nouvelles syntaxes à apprendre. Juste du Python standard et moderne.

Si vous souhaitez un rappel de 2 minutes sur l'utilisation des types en Python (même si vous ne comptez pas utiliser FastAPI), jetez un oeil au tutoriel suivant: [Python Types](python-types.md){.internal-link target=_blank}.

<div class="termy">

```console
$ python myapp.py
```

</div>

mais qui n'est pas appelé lorsqu'un autre fichier l'importe, comme dans :

```Python
from myapp import app
```

#### Pour davantage de détails

Imaginons que votre fichier s'appelle `myapp.py`.

Si vous l'exécutez avec :

<div class="termy">

```console
$ python myapp.py
```

</div>

```console
// Here we don't set the env var yet
$ python main.py

// As we didn't set the env var, we get the default value

Hello World from Python

// But if we create an environment variable first
$ export MY_NAME="Wade Wilson"

// And then call the program again
$ python main.py

// Now it can read the environment variable

Hello Wade Wilson from Python
```

</div>

////

//// tab | python 3.9+

```python hl_lines="18-19  26-27"
{!> ../../docs_src/dependencies/tutorial008_an_py39.py!}
```

////

//// tab | python 3.8+

```python hl_lines="17-18  25-26"
{!> ../../docs_src/dependencies/tutorial008_an.py!}
```

////

//// tab | python 3.8+ non-annotated

/// tip | Dica

Utilize a versão com `Annotated` se possível.

///

Теперь мы воспользуемся простой зависимостью, чтобы прочитать кастомизированный `X-Token` из заголовка:

//// tab | Python 3.9+

```Python hl_lines="3  6-8" title="app/dependencies.py"
{!> ../../docs_src/bigger_applications/app_an_py39/dependencies.py!}
```

////

//// tab | Python 3.8+

```Python hl_lines="1  5-7" title="app/dependencies.py"
{!> ../../docs_src/bigger_applications/app_an/dependencies.py!}
```

/// info

To receive uploaded files, first install <a href="https://github.com/Kludex/python-multipart" class="external-link" target="_blank">`python-multipart`</a>.

Make sure you create a [virtual environment](../virtual-environments.md){.internal-link target=_blank}, activate it, and then install it, for example:

```console
$ pip install python-multipart
```

This is because uploaded files are sent as "form data".

///