Question

class DBconnection {

    protected $connection;

    public function __construct(){
        $this->dbConnect();
    }

    public function dbConnect() {
        try {

            // Try and connect to the database, if a connection has not been established yet{
            // Load configuration as an array. Use the actual location of your configuration file
            $config = parse_ini_file("config.ini"); 
            $dsn = 'mysql:host='. $config['host'] .';dbname=' . $config['dbname'] . ';charset=utf8;';
            $this->connection = new PDO($dsn, $config['username'], $config['password']);

            //echo 'Connection to database has been successfull!';
            return $this->connection;

        } catch(Exception $e) {
            echo 'There was an error while connecting to the database!';
            $this->connection = NULL;
        }
    }

    public function disConnect(){
        $this->connection = NULL;
        //echo '<br>Database connection has been disconnected successfully!';
    }
}

class DBTransaction extends DBconnection {

    public function __construct(){
        parent::__construct();
    }

    // FETCH ALL DATA
    public function select_all($query) {
      try {
            $result = $this->connection->query($query);
                $result->execute();
                    return $result;

        } catch (PDOException $e) {
            throw new Exception($e->getMessage());  
        }
  }

  // FETCH SPECIFIC DATA
  public function select_specific($query, $params = []) {
    try {
            $result = $this->connection->prepare($query);
              $result->execute($params);
                return $result;

        } catch (PDOException $e) {
            throw new Exception($e->getMessage());  
        }
  }

  // EXECUTE INSERT, UPDATE, DELETE
    public function execute_query($query, $params = []) {
        try {
            $stmt = $this->connection->prepare($query);
                $stmt->execute($params);
                    return $stmt;   

        } catch (PDOException $e) {
            throw new Exception($e->getMessage());  
        }
    }
}

问题是我收到此错误：

PHP致命错误：在null中调用成员函数prepare（）第58行/home/pipedu/public_html/msgbrd/class/DBTransaction.php

我在哪里弄错了。当我在localhost上运行它时，它运行正常。

Answer 1

您使用connection在NULL内的catch区块中将班级的DBconnection::dbConnect()属性设置为$this->connection = NULL;。但是，在您的其他功能中，您不会检查它。不要因为而在你的班级中使其成为一个接受状态而引发错误。

您的解决方案是：

不要从类中的数据库连接中捕获异常，而是在初始化它的实例时捕获它并相应地处理它。像这样DBconnection->connection = NULL会成为你班上的非法状态，你可以在其他方法中忽略这种情况。

示例：

try {
    $con = new DBTransaction();
    $result = $con->select_all('SELECT * FROM table');
} catch (Exception $e) {
    $result = NULL;
}

Hande the state，DBconnection->connection在您的其他方法中NULL可能public function select_all($query) { if (this->connection === NULL) { return NULL; } $result = $this->connection->query($query); $result->execute(); return $result; }并返回并判断该案例的值：

示例：

language

PHP致命错误：调用成员函数prepare（）

1 个答案: