Question

我正在尝试使用oop类来获取用户信息，但我收到此错误

致命错误：在functions.php中的非对象上调用成员函数prepare（）

user.php - ＆gt;

include_once 'functions.php';
$user = new User();

echo $user->get_fullname(5);

functions.php - ＆gt;

include_once 'database.php';
class User 
{
    public function connect()
    {
        $dbh = new DB_Class();
    }

    public function get_fullname($uid)
    {

        $getName = $dbh->prepare("SELECT EmailAddress FROM users WHERE UserID =:username");
        $getName->bindParam(':username', $uid);
        $getName->execute();
        $rowName = $getName->fetch();
        $email = $rowName['emailaddress'];
        return $email;

    }    
}

database.php - ＆gt;

class DB_Class
{
    public function connect() {
        try {
            $dbh= new PDO("mysql:host=localhost;dbname=root",'users','password', array(
                PDO::ATTR_ERRMODE => PDO::ERRMODE_EXCEPTION,
                PDO::MYSQL_ATTR_INIT_COMMAND => "SET NAMES utf8"
            ));
        } catch (PDOException $e) {
            echo $e->getMessage();
        }

        $dbh->setAttribute(PDO::ATTR_ERRMODE,PDO::ERRMODE_WARNING);
        $dbh->setAttribute(PDO::ATTR_CASE,PDO::CASE_LOWER);
    }

}

我做错了什么：（

Answer 1

您实际上从未真正授予PDO实例$dbh对您尝试使用它的内容的访问权限。您似乎将类简单地用作函数分组，但也期望发生一些魔术： - ）这就是我用你现有的代码做的事情：

class DB_Class {

    protected $dsn;
    protected $user;
    protected $password;

    protected $connection;

    public function __construct($dsn = null, $user = null, $password = null)
    {
        $this->dsn = $dsn;
        $this->user = $user;
        $this->password = $password;
    }

    public function connect()
    {
       if($this->connection) {
         return $this->connection;
       }

       try {
         $this->connection = new PDO($this->dsn,$this->user, $this->password, 
            array(
              PDO::ATTR_ERRMODE => PDO::ERRMODE_EXCEPTION,
              PDO::MYSQL_ATTR_INIT_COMMAND => "SET NAMES utf8"
         ));

         $this->connection->setAttribute(PDO::ATTR_ERRMODE,PDO::ERRMODE_WARNING);
         $this->connection->setAttribute(PDO::ATTR_CASE,PDO::CASE_LOWER);

         return $this->connection;
       }
       catch (PDOException $e) {

          return false;
       }

    }
}

class User {
    protected $db;

    public function __construct(DB_Class $db = null) 
    {
        $this->db = $db;
    }

    public function setDb(DB_Class $db)
    {
       $this->db = $db;
    }



    public function get_fullname($uid)
    {
        $stmt = $this->db->connect()->prepare("SELECT EmailAddress FROM users WHERE UserID =:username");
        $stmt->execute(array(':username', $uid));
        if($row = $getName->fetch()) {
           return $row['emailaddress'];
        } else {
           return null;
        }
    }

}

Answer 2

$dbh变量未传递到get_fullname函数。你需要做类似的事情：

public function connect()
{
    $dbh = new DB_Class();
    return $dbh;
}

public function get_fullname($uid)
{
    $dbh = $this->connect();

Answer 3

您需要将$ dbh声明为User类的属性，并通过$ this identifier：

访问它

class User 
    {
protected $dbh;
    public function connect()
    {
    $this->dbh = new DB_Class();
    }

    public function get_fullname($uid)
    {

$getName =$this->dbh->prepare("SELECT EmailAddress FROM users WHERE UserID =:username");
$getName->bindParam(':username', $uid);
$getName->execute();
$rowName = $getName->fetch();
    $email = $rowMail['emailaddress'];
    return $email;

    }

    }

Answer 4

您实际上从未将类属性指定为属性，在声明方法内部的变量将它们放入方法当前作用域时，您正在做的就是在方法完成执行后销毁它们。

要在类中正确设置属性，您需要使用$this->varname声明它们，并且访问它们也是如此。

您还在为类构造使用了错误的名称，构造函数必须设置为__construct而不是connect。

正如您在更新的代码中所看到的，$dbh变量现在是User类的属性，可以在它的方法之间调用。

用户类

class User 
{
    public function __construct()
    {
        $this->dbh = new DB_Class();
    }

    public function get_fullname($uid)
    {

        $getName = $this->dbh->getConnection()->prepare("SELECT EmailAddress FROM users WHERE UserID =:username");
        $getName->bindParam(':username', $uid);
        $getName->execute();
        $rowName = $getName->fetch();
        $email = $rowName['emailaddress'];
        return $email;

    }    
}

数据库类

class DB_Class
{
    public function __construct() {
        try {
            $this->dbh = new PDO("mysql:host=localhost;dbname=root",'users','password', array(
                PDO::ATTR_ERRMODE => PDO::ERRMODE_EXCEPTION,
                PDO::MYSQL_ATTR_INIT_COMMAND => "SET NAMES utf8"
            ));
        } catch (PDOException $e) {
            echo $e->getMessage();
        }

        $this->dbh->setAttribute(PDO::ATTR_ERRMODE,PDO::ERRMODE_WARNING);
        $this->dbh->setAttribute(PDO::ATTR_CASE,PDO::CASE_LOWER);
    }

    public function getConnection() {
        return $this->dbh;
    }
}

使用http://us2.php.net/manual/en/oop5.intro.php作为资源，您将获益匪浅。

尝试从数据库获取用户信息时非对象的OOP PHP错误

4 个答案: