如果你已經知道什麼是「環境變數」並且知道如何使用它們，你可以放心跳過這一部分。

///

環境變數（也稱為「**env var**」）是一個獨立於 Python 程式碼**之外**的變數，它存在於**作業系統**中，可以被你的 Python 程式碼（或其他程式）讀取。

環境變數對於處理應用程式**設定**（作為 Python **安裝**的一部分等方面）非常有用。

## 建立和使用環境變數 { #create-and-use-env-vars }

你在 **shell（終端機）**中就可以**建立**和使用環境變數，並不需要用到 Python：

//// tab | Linux, macOS, Windows Bash

<div class="termy">

```console
// 你可以使用以下指令建立一個名為 MY_NAME 的環境變數
$ export MY_NAME="Wade Wilson"

// Copyright 2015 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package asm

import (
	"bufio"
	"bytes"
	"fmt"
	"internal/buildcfg"
	"os"
	"path/filepath"
	"regexp"
	"sort"
	"strconv"
	"strings"
	"testing"

	"cmd/asm/internal/lex"
	"cmd/internal/obj"
)

/*
 * Copyright 2012-2025 CodeLibs Project and the Others.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,

Önceki bu araçlardan edinilen deneyimler üzerine özellikleri, tip sistemi ve diğer kısımları geliştirip artırırken, **FastAPI**’yi APIStar’ın “ruhani varisi” olarak görüyorum.

///

## **FastAPI** Tarafından Kullanılanlar { #used-by-fastapi }

### [Pydantic](https://docs.pydantic.dev/) { #pydantic }

Pydantic, Python tip belirteçlerine dayalı olarak veri doğrulama, dönüşüm ve dökümantasyon (JSON Schema kullanarak) tanımlamak için bir kütüphanedir.

/*
 * Copyright 2012-2025 CodeLibs Project and the Others.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,

/*
 * Copyright 2012-2025 CodeLibs Project and the Others.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,

/*
 * Copyright (C) 2008 The Guava Authors
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,

이후 데이터를 변환하고 검증합니다. 그래서 그 `settings` 객체를 사용할 때는 선언한 타입의 데이터를 갖게 됩니다(예: `items_per_user`는 `int`가 됩니다).

### `settings` 사용하기 { #use-the-settings }

이제 애플리케이션에서 새 `settings` 객체를 사용할 수 있습니다:

{* ../../docs_src/settings/tutorial001_py310.py hl[18:20] *}

### 서버 실행하기 { #run-the-server }

///

接著，當你建立該 `Settings` 類別的實例（此處為 `settings` 物件）時，Pydantic 會以不區分大小寫的方式讀取環境變數，因此，即使環境變數是大寫的 `APP_NAME`，也會被讀入屬性 `app_name`。

然後它會轉換並驗證資料。因此，當你使用該 `settings` 物件時，你會得到你宣告的型別的資料（例如 `items_per_user` 會是 `int`）。

### 使用 `settings` { #use-the-settings }

接著你可以在應用程式中使用新的 `settings` 物件：

{* ../../docs_src/settings/tutorial001_py310.py hl[18:20] *}

### 執行伺服器 { #run-the-server }

接下來，你可以在啟動伺服器時，將設定以環境變數傳入。舉例來說，你可以設定 `ADMIN_EMAIL` 與 `APP_NAME`：

/*
 * Copyright 2012-2025 CodeLibs Project and the Others.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,