PHP报错：无法从外部调用DbOperations类的私有方法insertData()

嘿，我来帮你搞定这个报错！你遇到的Uncaught Error: Call to private method DbOperations::insertData() from context ''是个典型的权限问题，咱们一步步来解决。

问题回顾 #

你在尝试向数据库插入数据时触发了这个错误，先看看你的相关代码：

数据插入脚本

<?php 
require_once '../includes/DbOperations.php'; 
$response = array(); 
if($_SERVER['REQUEST_METHOD']=='POST'){ 
    if (isset($_POST['airport']) and isset($_POST['location']) and isset($_POST['space']) and isset($_POST['flight'])) { 
        //operate the data further// 
        $db = new DbOperations (); 
        $result = $db->insertData($_POST['airport'], $_POST['location'], $_POST['space'], $_POST['flight']); 
        if($result == 1){ 
            $response['error'] = false; 
            $response['message'] = "Task Inserting Successfully!!"; 
        } elseif ($result == 2) { 
            $response['error'] = true; 
            $response['message'] = "Some error occured please try again!!"; 
        } elseif ($result == 0) { 
            $response['error'] = true; 
            $response['message'] = "Data already Inserted!!"; 
        } 
    } else { 
        $response['error'] = true; 
        $response['message'] = "Required fields are missing!!"; 
    } 
}else { 
    $response['error'] = true; 
    $response['message'] = "Invalid Request!!"; 
} 
echo json_encode($response); 
?>

DbOperations类代码

<?php 
class DbOperations{ 
    private $con; 
    function __construct(){ 
        require_once dirname(__FILE__).'/DbConnect.php'; 
        $db = new DbConnect(); 
        $this->con = $db->connect(); 
    } 

    /*CRUD -> C -> CREATE */ 
    public function createUser($username, $pass, $email){ 
        if($this->isUserExist($username,$email)){ 
            return 0; 
        }else{ 
            $password = md5($pass); 
            $stmt = $this->con->prepare("INSERT INTO `users` (`id`, `username`, `password`, `email`) VALUES (NULL, ?, ?, ?);"); 
            $stmt->bind_param("sss",$username,$password,$email); 
            if($stmt->execute()){ 
                return 1; 
            } else { 
                return 2; 
            } 
        } 
    } 

    public function userLogin($username, $pass){ 
        $password = md5($pass); 
        $stmt = $this->con->prepare("SELECT id FROM users WHERE username = ? AND password = ?"); 
        $stmt->bind_param("ss", $username, $password); 
        $stmt->execute(); 
        $stmt->store_result(); 
        return $stmt->num_rows > 0; 
    } 

    public function getUserByUsername ($username){ 
        $stmt = $this->con->prepare ("SELECT * FROM users WHERE username = ?"); 
        $stmt->bind_param("s", $username); 
        $stmt->execute(); 
        return $stmt->get_result()->fetch_assoc(); 
    } 

    private function isUserExist($username, $email){ 
        $stmt = $this->con->prepare("SELECT id FROM users WHERE username = ? OR email = ?"); 
        $stmt->bind_param("ss", $username, $email); 
        $stmt->execute(); 
        $stmt->store_result(); 
        return $stmt->num_rows > 0; 
    } 

    /*CRUD -> C -> CREATE */ 
    private function insertData($airport, $location, $space , $flight){ 
        if($this->isDataExist($airport, $location, $space , $flight)){ 
            return 0; 
        } else { 
            $stmt = $this->con->prepare("INSERT INTO `users_detail` (`id`, `airport`, `location`, `space`, `flight`, `userid`) VALUES (NULL, ?, ?, ?, ?, NULL);"); 
            $stmt->bind_param("ssss",$airport, $location, $space , $flight); 
            if($stmt->execute()){ 
                return 1; 
            } else { 
                return 2; 
            } 
        } 
    } 
} 
?>

问题根源 #

这个错误的核心原因很简单：你在类的外部调用了一个私有方法。在PHP里，用private修饰的方法只能在类内部被调用，外部实例化对象后根本没权限访问。你在插入脚本里通过$db->insertData(...)调用了这个方法，但insertData在DbOperations类里被定义成了private function，这就触发了权限错误。

另外，我还发现一个隐藏问题：你的insertData方法里调用了isDataExist方法，但这个方法在你的类里根本没定义，就算解决了权限问题，后续也会报方法不存在的错误，得一起处理。

修复步骤 #

1. 修改insertData的访问权限
   把insertData方法的private改成public，这样外部脚本就能正常调用它了：

// 将private替换为public
public function insertData($airport, $location, $space , $flight){ 
    if($this->isDataExist($airport, $location, $space , $flight)){ 
        return 0; 
    } else { 
        $stmt = $this->con->prepare("INSERT INTO `users_detail` (`id`, `airport`, `location`, `space`, `flight`, `userid`) VALUES (NULL, ?, ?, ?, ?, NULL);"); 
        $stmt->bind_param("ssss",$airport, $location, $space , $flight); 
        if($stmt->execute()){ 
            return 1; 
        } else { 
            return 2; 
        } 
    } 
}

2. 添加缺失的isDataExist私有方法
   在DbOperations类里补充这个方法，用来检查users_detail表中是否已存在相同的数据，逻辑和isUserExist类似：

// 添加到DbOperations类中，比如放在isUserExist方法后面
private function isDataExist($airport, $location, $space , $flight){ 
    $stmt = $this->con->prepare("SELECT id FROM users_detail WHERE airport = ? AND location = ? AND space = ? AND flight = ?"); 
    $stmt->bind_param("ssss", $airport, $location, $space, $flight); 
    $stmt->execute(); 
    $stmt->store_result(); 
    return $stmt->num_rows > 0; 
}

验证修复 #

做完这两处修改后，再运行你的插入脚本，应该就能正常调用insertData方法完成数据插入了。如果还有其他报错，可以检查数据库连接是否正常，或者users_detail表的结构是否和你的SQL语句匹配。

内容的提问来源于stack exchange，提问作者Nurudin Mohd Shah