Proper way to access database in PHP classes - php

Question

My limited PHP knowledge is rather old. When I used to create websites I always had a config.php file which contained some defines and a $_DB global variable. Then in every function_xyz.php file I included this config file.
Now I want to finally move on and use classes. But I can't figure out a proper way to have access to mysql in functions of my classes without inclusion of the so called config.php file on top of each file.
Imagine I have a class called User.php:
class User {
private $firstName;
private $familyName;
private $emailAddress;
public function __construct($username, $password) {
//check if user with name and pass exist in DB
// stuff....
//If user exist, populate member variables
$this->emailAddress = ...
}
public function getEmail(){
return $this->emailAddress;
}
}
I know it is not the best example or practice...but how can I have a global MySQL access in all my classes without being required to have the config file included.
What is the best practice nowadays?

Answer 1

Make a global Instance:
//db.php include once
class DB {
#bind connenction in it
}
#make instance
$db = new DB($config);#use for User Instances
and then:
class User {
private $db;
private $firstName;
private $familyName;
private $emailAddress;
public function __construct($db) {
$this->db=$db;
}
public function validate($username, $password,$db) {
//check if user with name and pass exist in DB
//If user exist, populate member variables
$this->emailAddress = ...
}
public function getEmail(){
return $this->emailAddress;
}
}
$user = new User($db);
Is one way.
But you telling to less about how you want to use the classes.

Answer 2

I would go with PHPAcademy's login/register tutorial. He have DB class that handles almost anything you need. Here is sample of his code, slightly modified by me, but all credits to Alex Garrett.
<?php
class DB {
private static $_instance = null;
private $_pdo,
$_query,
$_error = false,
$_results,
$_count = 0;
private function __construct() {
try {
$this->_pdo = new PDO('mysql:host=' . Config::get('mysql/host') . ';dbname=' . Config::get('mysql/db'), Config::get('mysql/username'), Config::get('mysql/password'));
} catch(PDOException $e) {
die($e->getMessage());
}
}
public static function getInstance() {
if(!isset(self::$_instance)) {
self::$_instance = new DB();
}
return self::$_instance;
}
public function query($sql, $params = array()) {
$this->_error = false;
if($this->_query = $this->_pdo->prepare($sql)) {
$x = 1;
if(count($params)) {
foreach($params as $param) {
if (is_int($param)) {
$this->_query->bindValue($x, $param, PDO::PARAM_INT);
} else {
$this->_query->bindValue($x, $param);
}
$x++;
}
}
if($this->_query->execute()) {
$this->_results = $this->_query->fetchAll(PDO::FETCH_OBJ);
$this->_count = $this->_query->rowCount();
}
else {
$this->_error = true;
print_r($this->_query->errorInfo());
}
}
return $this;
}
public function action($action, $table, $where = array()) {
if(count($where) === 3){
$operators = array('=', '>', '<', '>=', '<=', '!=');
$field = $where[0];
$operator = $where[1];
$value = $where[2];
if(in_array($operator, $operators)) {
$sql = "{$action} FROM {$table} WHERE {$field} {$operator} ?";
if(!$this->query($sql, array($value))->error()) {
return $this;
}
}
} else if (count($where) === 0) {
$sql = "{$action} FROM {$table}";
if(!$this->query($sql)->error()) {
return $this;
}
}
return false;
}
public function get($table, $where) {
return $this->action('SELECT *', $table, $where);
}
public function delete($table, $where) {
return $this->action('DELETE', $table, $where);
}
public function getAll($table) {
return $this->action('SELECT *', $table);
}
public function first() {
return $this->results()[0];
}
public function last() {
$i = count($this->results()) - 1;
return $this->results()[$i];
}
public function insert($table, $fields = array()) {
if(count($fields)) {
$keys = array_keys($fields);
$values = '';
$x = 1;
foreach ($fields as $field) {
$values .= '?';
if($x < count($fields)) {
$values .= ', ';
}
$x++;
}
$sql = "INSERT INTO {$table} (`" . implode('` , `', $keys) . "`) VALUES({$values})";
if (!$this->query($sql, $fields)->error()) {
return true;
}
}
return false;
}
public function update($table, $where, $parametar, $fields) {
$set = '';
$x = 1;
foreach ($fields as $name => $value) {
$set .= "{$name} = ?";
if ($x < count($fields)) {
$set .= ', ';
}
$x++;
}
if (is_int($parametar)) {
$sql = "UPDATE {$table} SET {$set} WHERE {$where} = {$parametar}";
} else {
$sql = "UPDATE {$table} SET {$set} WHERE {$where} = '{$parametar}'";
}
if (!$this->query($sql, $fields)->error()) {
return true;
}
return false;
}
public function results() {
return $this->_results;
}
public function error() {
return $this->_error;
}
public function count() {
return $this->_count;
}
}
Then you can query database like DB::getInstance()->getAll('tableName')->results();. Change DB credentials in __construct, or watch his videos (which I recomend).