conecting to db with php class

[farhad]

Code: Select all

   class connect
{
   private static $_dbUser = 'admin-book';
   private static $_dbPass = '389856';
   private static $_dbDB = 'zadmin_book';
   private static $_dbHost = 'localhost';
   private static $_connection = NULL;

   /**
    * Constructor
    * prevents new Object creation
    */

   private function __construct(){
   }

   /**
    * Get Database connection
    *
    * @return Mysqli
    */

   public static function getConnection() {
      if (!self::$_connection) {
     self::$_connection = @new mysqli(self::$_dbHost, self::$_dbUser, self::$_dbPass, self::$_dbDB);
   
         if (self::$_connection -> connect_error) {
            die('Connect Error: ' . self::$_connection->connect_error);
         }
      }
      return self::$_connection;
   }
}

I had used that code and put it into file and named it db.php
then i wrote below code but it doesn't work-Thanks for any help

Code: Select all

$connection = connect::getConnection();

$result = $connection->query($query);

$query = "SELECT * from  pages";
if ($result = $mysqli->query($query)) {

    /* fetch object array */
    while ($row = $result->fetch_row()) {
     
$imgsrc=$row[1];

echo '<tr><td>'.$row[0].'</td><td>'.$row[1].'</td><td>text</td><td>book1</td></tr>';
echo '</div>';         
         }
             /* free result set */
    $result->close();
}
$mysqli->close();


[seandisanti]

Could you be more specific as to what's going on when it 'doesn't work'. Is it returning an error? If so, what error? Here's the Database.php that I typically use. it is using PDO, (faster and more secure than mysql_ or mysqli_ functions). The connection parameters are declared in a constants.php, and this class is loaded as necessary from an autoloader in another file.It is very easy to implement though, and then just call $db = Database::getInstance(); and you have a new PDO object and all of the functionality that offers.

Code: Select all

<?php
/*
 * Database class only one connection is allowed.
 */

class Database extends PDO{

    private $connection;
    private static $instance;

    public static function getInstance() {
        if (!self::$instance) {
            
            self::$instance = new self("mysql:host=". DBHOST . ";dbname=".DB,DBUSER,DBPASSWORD);
        }
        return self::$instance;
    }

    /*
     * empty clone magic method to prevent duplication
     *
     */

    private function __clone() {

    }

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

}
 

[farhad]

thanks for your help ,problem solved-
just one thing that I couldn't get:
It works whether the below code is written or not in connect class
so what's this code's operation?

Code: Select all

 private function __construct() {
   }


regard

[seandisanti]

well that declaration is an invalid one. __construct is a magic method that runs when an object of a class is instantiated. but as a magic method, it is public static rather than private, but you only really need to write 'function __construct(){}' because as a magic method the access level is already predetermined. When you are instantiating an object that has properties that need to be set, the __construct() method is the place to do that, or to call an initialization method. Here's an example of a typical constructor i use in a lot of classes.

Code: Select all



    function __construct($data = array()) { //receives an array of data to populate the parameters
        if (!is_array($data) == TRUE) {
            return false; //returns false if array isn't passed
        }
        if (count($data) > 0) {//step through the array
            foreach ($data as $name => $value) {
                $this->__SET($name, $value);//my __set function verifies that the property exists, and sets it to the passed value if it does
            }
        }
        $db = Database::getInstance();
        if (isset($this->id)){//assuming the object was instantiated from an array so already exists in db
            $sql = "SELECT 
                        t.descr as title,
                        l.descr as location,
                        concat_ws(' ',u.first_name,u.last_name) as reports_to,
                        d.descr as department, 
                        st.descr as status 
                    FROM 
                    job j inner join job_locations l ON j.location_id=l.id 
                    INNER JOIN job_departments d on j.department_id=d.id 
                    INNER JOIN users u on j.reports_to_id = u.id 
                    INNER JOIN job_titles t ON j.title_id = t.id 
                    INNER JOIN job_status st ON j.status_id = st.id
                    WHERE j.id=" . $db->quote($this->id);
            $result = $db->query($sql);
            if (!$result || $result->rowCount()==0){
                return false;//no records found
            }//this sets the relevant properties based on the result of the query above
            $results=$result->fetch(PDO::FETCH_ASSOC);
            $this->title = $results['title'];
            $this->department = $results['department'];
            $this->location = $results['location'];
            $this->reports_to = $results['reports_to'];
            $this->status = $results['status'];
        }
        return $this;//$this is now a valid object with all fields populated.  give it back
        
    }