Hello. I am trying to create a database connection class.
For the connection I will have a filename config.inc.php. This will have all the parameters to pass to the new connection.
The next file is database_connection.php file. This file will have various variables and constructor for the connection. Also withing the database conneciton class, one the connection is etablished I would like to return the connection as a $link so I can use it in my queries in my php files.
Last I will have the database_query class in another file where I will have all the queries that will use the $link as the connection.
For some reasone I can get all the classed to work together. Any suggestions on how I could implement this. Thank you
<?php
class Database
{
var $host = ""; //database server
var $user = ""; //database login name
var $pass = ""; //database login password
var $database = ""; //database name
public $link;
public function Database($host, $user, $pass, $database)
{
$this->host=$host;
$this->user=$user;
$this->pass=$pass;
$this->database=$database;
}
public function connect()
{
$this->link = new mysqli($this->host,$this->user,$this->pass,$this->database);
if (mysqli_connect_error())
{
echo mysqli_connect_error();
exit();
}
else
return $this->link;
}
}
?>
For example I have a function getData() in database.php file that worked when the database connection was within this file. the function selects all the data but uses $link which is the connection.
$stmt = $this->link->prepare("SELECT * FROM Users");
I guess it is not working because it can’t get the connection link.
Creating a new instance of the database_query class where all my functions are, and calling a function, and it just doesn’t display anything. As I sayed, when this code was in my class where all the functions where, it all worked.
public $link;
public function connect()
{
$link = new mysqli("localhost","root","root","Users");
if (mysqli_connect_error())
{
echo mysqli_connect_error();
exit();
}
else
$this->link = $link;
}
Then I just use the link for all of my functions as shown above…
I can’t see how the database connection in the $link variable is getting in to the database_query object, yet the getData() method refers to it as $this->link on its first line.
You store a link in object of Database class, but trying to access it in object of database_query class. That is wrong, because in database_query there is no $this->link (cuz you made that link in another class, not that one).
So you should pass your link from Database to database query, for example:
require "config.inc.php";
require "database_connection.php";
require_once ('database.php');
$conn = new Database(DB_SERVER, DB_USER, DB_PASS, DB_DATABASE);
$link = $conn->connect();
$query = new database_query($link); // -- passing $link here to constructor
$array = $query->getData();
and in database.php leave only class definition with new constructor:
class database_query {
private $link; // here you'll store link from Database
public function __construct($link){
$this->link = $link;
}
public function getData(){
// now $this->link is available here
// and contains correct link
}
}
Maybe doing something like the following would be easier?
<?php
class Database {
private $_connection;
// Store the single instance.
private static $_instance;
// Get an instance of the Database.
// @return Database:
public static function getInstance() {
if (!self::$_instance) {
self::$_instance = new self();
}
return self::$_instance;
}
// Constructor - Build the mysqli Connection:
public function __construct() {
$this->_connection =new mysqli($this->host,$this->user,$this->pass,$this->database);
if ($this->_connection->connect_error) {
die('Connect Error (' . $this->_connection->connect_errno . ') ' . $this->_connection->connect_error);
}
}
// Empty clone magic method to prevent duplication:
private function __clone() {
}
// Get the PDO connection:
public function getConnection() {
return $this->_connection;
}
}
/* How to use the Database Class */
$connect = Database::getInstance(); // Get the Database Instance:
$myCon = $connect->getConnection(); // Setup the Database Connection:
The suggestion for a singleton instance in a database connection class is a reasonable one, but that’s a rather buggy implementation I’m afraid. Sorry! (die() function in the constructor, __construct declared as public, no static init method to get the connection params in there in the first place).
Using a dependency injection container would be better than using a singleton but I think that would just be muddying the waters at this stage. Maybe it would be better if the OP gets some working code first and then learns how to progress?
<?php
class database_query{
private $link;
public function __construct($link)
{
$this->link = $link;
}
public function getData()
{
$stmt = $this->link->prepare("SELECT * FROM Users");
$stmt->bind_param();
if ($stmt->execute())
{
$result = $stmt->get_result();
while($row = $result->fetch_array(MYSQLI_ASSOC))
{
$row = array_map('stripslashes', $row);
$dataArray[] = $row;
}
}
return $dataArray;
}
}
And this is where the connection is made:
DATABASE_CONNECTION.PHP
<?php
class Database
{
var $host = ""; //database server
var $user = ""; //database login name
var $pass = ""; //database login password
var $database = ""; //database name
public $link;
public function Database($host, $user, $pass, $database)
{
$this->host=$host;
$this->user=$user;
$this->pass=$pass;
$this->database=$database;
}
public function connect()
{
$this->link = new mysqli($this->host,$this->user,$this->pass,$this->database);
if (mysqli_connect_error())
{
echo mysqli_connect_error();
exit();
}
else
return $this->link;
}
}
?>
