Question

我是PHP新手。

class metacountry
{
  public $mysqli;
  function metacountry()
  {

    global $config;
    $mysqli=new mysqli($config['DBHostName'],$config['DBUserName'],$config['DBPassword'],$config['DBName']);
   $mysqli->set_charset("utf8");
   if (mysqli_connect_errno()) {

      printf("Connect failed: %s\n", mysqli_connect_error());
      exit();

    }

  }

  function InsertCountry()
  {

    $stmt=$mysqli->prepare("insert into tbl_metacountry values(?,?,?,?,?)");
    $stmt->bind_param('sssss', $country, $meta_title, $meta_keywords, $meta_description, $active);
    $country=addslashes(addcslashes($mysqli->real_escape_string($_POST['country'], "%_")));
    $meta_title=addslashes(addcslashes($mysqli->real_escape_string($_POST['meta_title'], "%_")));
    $meta_keywords=addslashes(addcslashes($mysqli->real_escape_string($_POST['meta_keywords'], "%_")));
    $meta_description=addslashes(addcslashes($mysqli->real_escape_string($_POST['meta_description'], "%_")));
    $meta_active=addslashes(addcslashes($mysqli->real_escape_string($_POST['active'], "%_")));
    $stmt->execute();
    $stmt->close();

  }

 }

它会抛出错误：

致命错误：在/var/www/html/country.php中调用null上的成员函数prepare（）

Answer 1

您必须使用$this来引用类属性。

你的联系：

$mysqli=new mysqli($config['DBHostName'],$config['DBUserName'],$config['DBPassword'],$config['DBName']);

应该是，

$this->mysqli[...]

其他信息

您应该在类中定义数据库设置，而不是使用global，以使其更多 OO。

阅读材料

Class Properties

Answer 2

我希望以下内容有意义 - 它没有经过测试，但看起来或多或少是正确的。数据库连接是在公共构造函数中创建的，并且为了清楚起见使用$this->conn引用 - 尽管您当然可以将其重命名为您想要的任何内容。

<?php
    class metacountry{
        private $conn;
        private $config;

        public function __construct($config=array()){
            /* initialise actual values at runtime */
            $this->config=(object)array_merge(array(
                'DBHostName'    =>  false,
                'DBUserName'    =>  false,
                'DBPassword'    =>  false,
                'DBName'        =>  false
            ),$config);


            $this->conn=new mysqli( $this->config->DBHostName, $this->config->DBUserName, $this->config->DBPassword, $this->config->DBName );
            $this->conn->set_charset("utf8");

            if( $this->conn->connect_errno ) {
                printf( "Connect failed: %s\n", $this->conn->connect_error );
                exit();
            }       
        }



        function InsertCountry(){
            $stmt=$this->conn->prepare("insert into `tbl_metacountry` values (?,?,?,?,?)");
            $stmt->bind_param('sssss', $country, $meta_title, $meta_keywords, $meta_description, $active );

            $country=addslashes( addcslashes( $this->conn->real_escape_string( $_POST['country'], "%_" ) ) );
            $meta_title=addslashes( addcslashes( $this->conn->real_escape_string( $_POST['meta_title'], "%_" ) ) );
            $meta_keywords=addslashes( addcslashes( $this->conn->real_escape_string( $_POST['meta_keywords'], "%_" ) ) );
            $meta_description=addslashes( addcslashes( $this->conn->real_escape_string( $_POST['meta_description'], "%_" ) ) );
            $meta_active=addslashes( addcslashes( $this->conn->real_escape_string( $_POST['active'], "%_" ) ) );

            $stmt->execute();
            $stmt->close();
        }
    } 



    /* example */
    $config=array(
        'DBHostName'=>'localhost',
        'DBUserName'=>'root',
        'DBPassword'=>'password',
        'DBName'    =>'mydb'
    );
    $meta=new metacountry( $config );
    if( $_SERVER['REQUEST_METHOD']=='POST' ) $meta->InsertCountry();
    $meta=null;
?>

mysqli在课堂上不起作用

2 个答案: