如何在同一API端点处理多个不同请求

async function getSpecialties(){
  let res = await fetch ('http://server-npk-web-core/specialties'); // 请求专业列表
  let specialties = await res.json();
  // ... 处理 specialties 数据
}

async function getSubjectsSpecial(){
  let res = await fetch ('http://server-npk-web-core/specialties'); // 请求特定专业科目
  let subjectsSpecial = await res.json();
  // ... 处理 subjectsSpecial 数据
}

// index.php
if($method === 'GET'){
  if($type === 'subjects'){
    getSubjects($pdo);
  } elseif($type === 'specialties'){
    getSpecialties($pdo); // 可能会同时调用，导致输出混乱
    getSubjectsSpecial($pdo);
  }
}

// specialties.php (包含具体数据获取逻辑)
function getSpecialties($pdo){
  $specialties = 'SELECT * FROM `specialties`';
  $stmt = $pdo -> query($specialties);
  $specialtiesList = [];
  while ($special = $stmt->fetch()){
    $specialtiesList[] = $special;
  }
  echo json_encode($specialtiesList); // 输出JSON
}

function getSubjectsSpecial($pdo){
  $subjectsSpecial = 'SELECT `subjects`.`title` FROM `subjects` WHERE `id_specialties` = 2';
  $stmt = $pdo -> query($subjectsSpecial);
  $subjectsSpecialList = [];
  while ($subjectSpecial = $stmt->fetch()){
    $subjectsSpecialList[] = $subjectSpecial;
  }
  echo json_encode($subjectsSpecialList); // 输出JSON
}

<script>
    async function getSpecialties(){
      // 请求专业列表时，添加 action=specialties
      let res = await fetch ('http://server-npk-web-core/specialties?action=specialties');
      let specialties = await res.json();
      console.log('专业列表:', specialties);
      // ... 处理 specialties 数据
    }

    async function getSubjectsSpecial(){
      // 请求特定专业科目时，添加 action=subjectsspecial
      let res = await fetch ('http://server-npk-web-core/specialties?action=subjectsspecial');
      let subjectsSpecial = await res.json();
      console.log('特定专业科目:', subjectsSpecial);
      // ... 处理 subjectsSpecial 数据
    }

    // 示例调用
    // getSpecialties();
    // getSubjectsSpecial();
</script>

<?php
    //-------------------------------
    // server-npk-web-core/specialties (此文件或路由处理文件)
    //-------------------------------

    // 假设 $pdo 已经初始化并连接到数据库
    // 例如：$pdo = new PDO('mysql:host=localhost;dbname=your_db', 'user', 'password');

    /**
     * 获取所有专业列表
     * @param PDO $pdo 数据库连接对象
     */
    function getSpecialties($pdo){
      $specialties = 'SELECT * FROM `specialties`';
      $stmt = $pdo -> query($specialties);
      $specialtiesList = [];
      while ($special = $stmt->fetch(PDO::FETCH_ASSOC)){ // 使用PDO::FETCH_ASSOC获取关联数组
        $specialtiesList[] = $special;
      }
      header('Content-Type: application/json'); // 明确指定响应头为JSON
      echo json_encode($specialtiesList);
    }

    /**
     * 获取特定专业下的科目列表 (示例中 id_specialties = 2)
     * @param PDO $pdo 数据库连接对象
     */
    function getSubjectsSpecial($pdo){
      // 注意：实际应用中，id_specialties 应该从请求参数中获取，而不是硬编码
      $subjectsSpecial = 'SELECT `subjects`.`title` FROM `subjects` WHERE `id_specialties` = 2';
      $stmt = $pdo -> query($subjectsSpecial);
      $subjectsSpecialList = [];
      while ($subjectSpecial = $stmt->fetch(PDO::FETCH_ASSOC)){
        $subjectsSpecialList[] = $subjectSpecial;
      }
      header('Content-Type: application/json'); // 明确指定响应头为JSON
      echo json_encode($subjectsSpecialList);
    }

    // 核心路由逻辑
    if( !empty( $_GET['action'] ) ){
        switch( $_GET['action'] ){
            case 'specialties':
                getSpecialties($pdo);
            break;
            case 'subjectsspecial':
                getSubjectsSpecial( $pdo );
            break;
            default:
                // 处理未知 action 的情况，返回错误信息
                header('Content-Type: application/json');
                http_response_code(400); // Bad Request
                echo json_encode(['error' => 'Invalid action specified']);
            break;
        }
    } else {
        // 如果没有指定 action 参数，也可以定义一个默认行为，或返回错误
        header('Content-Type: application/json');
        http_response_code(400); // Bad Request
        echo json_encode(['error' => 'Action parameter is missing']);
    }
?>