CODEWITHSUNDEEP
php
Chan
Chan

Reputation: 1969

PHP class inherit parent issue

config.php

<?php
define('DB_HOST', 'localhost');
define('DB_DB', 'db');
define('DB_USERNAME', 'root');
define('DB_PASSWORD', '123456');

class.main.php

<?php
class main {
    var $host     = '';
    var $db       = '';
    var $username = '';
    var $password = '';
    var $conn = '';

    public function __construct() {
        $this->host = DB_HOST;
        $this->db = DB_DB;
        $this->username = DB_USERNAME;
        $this->password = DB_PASSWORD;
    }

    /**
     * Connect to database
     */
    function connect() {
        $this->conn = mysql_connect($this->host, $this->username, $this->password) or trigger_error(mysql_error(), E_USER_ERROR);
        mysql_query("SET NAMES 'utf8'");
    }

    public function myRow($sql) {
        mysql_select_db($this->db, $this->conn);
        $rec = mysql_query($sql, $this->conn) or die(mysql_error());
        $row = mysql_fetch_assoc($rec);
        $count = mysql_num_fields($rec);

        if ($this->recordCount > 0) {
            $result = array();
            $temp = array();

            do {
                for ($i = 0; $i < $count; $i++) {
                    $name = mysql_field_name($rec, $i);
                    $temp[$name] = $row[$name];
                }

                array_push($result, $temp);
            } while($row = mysql_fetch_assoc($rec));
        } else {
            $result = NULL;
        }

        mysql_free_result($rec);
        return $result;
    }
}

This a part of my class, if I want to get data, it's like

<?php
include 'config.php';
include 'class.main.php';
$main = new main;
$main->connect();
$sql = 'SELECT * FROM table';
$row = $main->myRow($sql);

Sometimes I will make other class for different case, some of the class might need to use myRow function, this is how I did now.

class.sub.php

<?php
class sub extends main {

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

   /**
     * Get member information
     *
     * @param integer $id member id
     * @return data
     */
    public function member($id = NULL) {
        $this->connect();

        if (NULL === $id) {
            $id = $_SESSION['memberId'];
        }

        $sql = "SELECT *
            FROM `members`
            WHERE `on` = 1";
        return $this->myRow($sql);
    }
}

<?php
include 'config.php';
include 'class.main.php';
$main = new main;
include 'class.sub.php';
$sub = new sub;
$main->connect();

$sql = 'SELECT * FROM table';
$row = $main->myRow($sql);

$member = $sub->member();
echo $member['xxx'];

It's work right now, all I concerned is I call $this->connect in member function again otherwise I can't get the connection from main class, but it means I connect to database twice in one page, it such a resource wasted, how to fix it?

Upvotes: 1

Views: 73

Answers (2)

developerCK
developerCK

Reputation: 4506

To solve this issue, You should read the "Design Patter". Specially "Singleton Pattern". Generally this pattern is used when we make such classes.

Basic is, In this pattern,

We can have only one object of that class in whole application at a time.

Read this is simple and very clear example. http://kazymjir.com/blog/singleton-pattern-php-example-tutorial/

Upvotes: 1

msg7086
msg7086

Reputation: 461

Try add var $conn = NULL; in the parent class.

This explicitly declare it as a public variable and can be inherited.

Upvotes: 0

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