///

Here we define the config `env_file` inside of your Pydantic `Settings` class, and set the value to the filename with the dotenv file we want to use.

### Creating the `Settings` only once with `lru_cache`

///

Aqui definimos a configuração `env_file` dentro da classe `Settings` do Pydantic, e definimos o valor como o nome do arquivo dotenv que queremos utilizar.

### Declarando `Settings` apenas uma vez com `lru_cache`

```
http://127.0.0.1:8000/items/?item-query=foobaritems
```

Mais `item-query` n'est pas un nom de variable valide en Python.

Le nom le plus proche serait `item_query`.

Mais vous avez vraiment envie que ce soit exactement `item-query`...

Pour cela vous pouvez déclarer un `alias`, et cet alias est ce qui sera utilisé pour trouver la valeur du paramètre :

pkg syscall (windows-386), type ProcessEntry32 struct
pkg syscall (windows-386), type ProcessEntry32 struct, DefaultHeapID uintptr
pkg syscall (windows-386), type ProcessEntry32 struct, ExeFile [260]uint16
pkg syscall (windows-386), type ProcessEntry32 struct, Flags uint32
pkg syscall (windows-386), type ProcessEntry32 struct, ModuleID uint32
pkg syscall (windows-386), type ProcessEntry32 struct, ParentProcessID uint32

```

### 从 `.env` 文件中读取设置

然后，您可以使用以下方式更新您的 `config.py`：

```Python hl_lines="9-10"
{!../../docs_src/settings/app03/config.py!}
```

在这里，我们在 Pydantic 的 `Settings` 类中创建了一个名为 `Config` 的类，并将 `env_file` 设置为我们想要使用的 dotenv 文件的文件名。

/// tip

`Config` 类仅用于 Pydantic 配置。您可以在<a href="https://docs.pydantic.dev/latest/api/config/" class="external-link" target="_blank">Pydantic Model Config</a>中阅读更多相关信息。

///

    return new byte[BUFFER_SIZE];
  }

  /**
   * There are three methods to implement {@link FileChannel#transferTo(long, long,
   * WritableByteChannel)}:
   *
   * <ol>
   *   <li>Use sendfile(2) or equivalent. Requires that both the input channel and the output
   *       channel have their own file descriptors. Generally this only happens when both channels

pkg syscall (darwin-386), const ENETDOWN = 50
pkg syscall (darwin-386), const ENETRESET = 52
pkg syscall (darwin-386), const ENETUNREACH = 51
pkg syscall (darwin-386), const ENFILE = 23
pkg syscall (darwin-386), const ENOATTR = 93
pkg syscall (darwin-386), const ENOBUFS = 55
pkg syscall (darwin-386), const ENODATA = 96
pkg syscall (darwin-386), const ENODEV = 19
pkg syscall (darwin-386), const ENOEXEC = 8

pkg syscall (netbsd-arm64-cgo), const ENETDOWN = 50
pkg syscall (netbsd-arm64-cgo), const ENETRESET = 52
pkg syscall (netbsd-arm64-cgo), const ENETUNREACH = 51
pkg syscall (netbsd-arm64-cgo), const ENFILE = 23
pkg syscall (netbsd-arm64-cgo), const ENOATTR = 93
pkg syscall (netbsd-arm64-cgo), const ENOATTR Errno
pkg syscall (netbsd-arm64-cgo), const ENOBUFS = 55
pkg syscall (netbsd-arm64-cgo), const ENODATA = 89

pkg syscall (freebsd-arm64), const ENETDOWN = 50
pkg syscall (freebsd-arm64), const ENETRESET = 52
pkg syscall (freebsd-arm64), const ENETUNREACH = 51
pkg syscall (freebsd-arm64), const ENFILE = 23
pkg syscall (freebsd-arm64), const ENOATTR = 87
pkg syscall (freebsd-arm64), const ENOATTR Errno
pkg syscall (freebsd-arm64), const ENOBUFS = 55
pkg syscall (freebsd-arm64), const ENODEV = 19

pkg syscall (darwin-arm64), const ENETDOWN = 50
pkg syscall (darwin-arm64), const ENETRESET = 52
pkg syscall (darwin-arm64), const ENETUNREACH = 51
pkg syscall (darwin-arm64), const ENFILE = 23
pkg syscall (darwin-arm64), const ENOATTR = 93
pkg syscall (darwin-arm64), const ENOATTR Errno
pkg syscall (darwin-arm64), const ENOBUFS = 55
pkg syscall (darwin-arm64), const ENODATA = 96