登录/注册系统获取致命错误php

Question

我已经写了一个代码，并有一个错误，我得到谁能告诉我什么是错的请吗？

错误致命错误：调用一个成员函数错误（c）中的非对象上：\ XAMPP \ htdocs中\ loginsistem \的index.php上线6

，但应该说OK！如果IM权

的init.php：

<?php 
session_start(); 

$GLOBALS ['config'] = array(
    'mysql' => array(
     'host' => '127.0.0.1', 
     'username' => 'root', 
     'password' => '', 
     'db' => 'lr' 
    ), 
    'remember' => array(
     'cookie_name' => 'hash', 
     'cookie_expiry' => 604800 
    ), 
    'session' => array(
     'session_name' => 'user' 
    ) 
); 

spl_autoload_register(function($class) { 
    require_once 'classes/' . $class . '.php'; 

}); 

require_once 'functions/sanitize.php'; 
?> 

的index.php：

<?php 
require_once 'core/init.php'; 

$user =DB::getInstance()->get('users', array('username', '=', 'grega')); 

if($user->error()) { 
    echo 'No user'; 
} else { 
    echo 'OK!'; 
} 

?> 

db.php中

<?php 
class DB { 
    private static $_instance = null; 
    private $_pdo, 
      $_query, 
      $error = false, 
      $_results, 
      $count = 0; 

    private function __construct() { 
     try { 
      $this->_pdo = new PDO('mysql:host=' . Config::get('mysql/host') .';dbname=' . Config::get('mysql/db'), Config::get('mysql/username'), Config::get('mysql/password')); 
     } catch (PDOException $e) { 
     die($e->getMessage()); 
     } 
    } 

    public static function getInstance() { 
     if(!isset(self::$_instance)) { 
      self::$_instance = new DB(); 
     } 
     return self::$_instance; 
    } 

    public function query($sql, $params = array()) { 
     $this->_error = false; 
     if($this->_query = $this->_pdo->prepare($sql)) { 
      $x = 1; 
      if(count($params)) { 
       foreach($params as$param) { 
        $this->_query->bindValue($x, $param); 
        $x++; 
       } 
      } 
      if($this->_query->execute()) { 
       $this->_results = $this->_query->fetchAll(PDO::FETCH_OBJ); 
       $this->_count = $this->_query->rowCount(); 
      } else { 
       $this->_error = true; 
      } 
     } 
     return $this; 
    } 

    public function action($action, $table, $where = array()) { 
     if(count($where) === 3) { 
      $operators = array('=', '>', '<', '>=', '<='); 

      $field  = '$where[0]'; 
      $operator = '$where[1]'; 
      $value  = '$where[2]'; 

      if(in_array($operator, $operators)) { 
       $sql = "{$action} FROM {$table} WHERE {$field} {$operator} ?"; 

       if($this->query($sql, array($value))->error()) { 
        return $this; 
       } 
      } 
     } 
     return false; 
    } 
    public function get($table, $where) { 
     return $this->action('SELECT *', $table, $where); 
    } 
    public function delete($table, $where) { 
     return $this->action('DELETE', $table, $where); 
    } 

    public function error() { 
     return $this->_error; 
    } 

} 

Answer 1

这也可能是在这一部分：

if($this->query($sql, array($value))->error()) { 
    return $this; 
} 

在我看来，你应该修改它：

if(! $this->query($sql, array($value))->error()) { 
    return $this; 
} 

Answer 2

拆分这样的代码：

// get db instance 
$db = DB::getInstance(); 
// the get function will return $this or false 
$users = $db->get('users', array('username', '=', 'grega')); 

if($users === false || $db->error()) { 
    echo 'No user'; 
} else { 
    echo 'OK!'; 
} 

我也看到在你的代码很奇怪，当你赋值：

$field  = $where[0]; 
$operator = $where[1]; 
$value  = $where[2]; 

如果删除“我认为这将更好地工作。

此外，如果您在代码上进行测试，则不需要在函数中测试错误。

if(in_array($operator, $operators)) { 
    $sql = "{$action} FROM {$table} WHERE {$field} {$operator} ?"; 

    $this->query($sql, array($value); 
    return $this; 
}