I have 2 classes and I would like to have 1 more for comfort :)
So I have class for database and system. I would like to have 3rd classs for functions. This class MUST use functions from database since there are SQL Queries. This is What I ended with:
class database {
public function __construct() {
$this->mysqli = new mysqli('localhost', 'root', '', 'roids');
$this->func = new functions();
}
}
class functions {
function __construct(){
$db = new database();
}
public function banned() {
$q = $db->select($this->prefix."banned", "*", "banned_ip", $this->getIP());
if (0 == 0) {
header('Location: banned.php'); // For testing
}
}
}
And I this kind of version ends in cycle. Any solutions ? Thanks a lot
Some of your classes must be a source, so other classes may use instances of it.
Let me show you one example:
class DataBase { //THIS class is a source.
public $mysqli ;
public function __construct(){
$this->mysqli = new mysqli('localhost', 'root', '', 'roids');
$this->mysqli->set_charset("utf-8") ;
}
public function ready(){
return ($this->mysqli instanceof MySQLi && $this->mysqli->ping()) ;
}
}
class User {
protected $db;
public function __construct(DataBase $db){
$this->db = $db ; //Now you can use your source
}
public function isBanned(){
if ($this->db->ready()){
$result = $this->db->mysqli->query("SELECT id FROM banned WHERE name='Hacker' ; ") ;
return ($result && $result->num_rows >= 1) ;
}
return false ;
}
}
Then instantiate the source and give it to instance of User:
$database = new DataBase() ;
$user = new User($database) ;
Now you can use a more complexed function:
if ($user->isBanned()) exit("You are banned") ;
The same way you can make class Functions and use it (other classes may use it) as a source.
Related
I have a class with a connection to a database
$db = new db();
class db {
public $server = 'localhost';
public $user = '';
public $passwd = '******';
public $db = '';
public $dbCon;
function __construct() {
$this->dbCon = mysqli_connect($this->server, $this->user, $this->passwd, $this->db);
}
function __destruct() {
mysqli_close($this->dbCon);
}
}
Now i want to make an other class and using the connection like this:
class Categories (
function GetCategory($cat) {
$myQuery = "SELECT * FROM test GROUP BY $cat";
$results = mysqli_query($this->dbCon, $myQuery);
return $results;
}
)
How can i use the connection in a other class?
Can somebody help me out whit this?
Make the $dbCon in your db class a static variable, so you can access it from category's using db::$dbcon as the connection variable. You could also make a static function returning the static dbcon variable, usefull tot check if it is actually a link and not null.
This is just one solution of many possibilities, but probably the easiest to implement because it isn't likely you need more connections to a db, so a static is perfect for it.
A static is nothing more then a variable living in the namespace it is defined in, you don't need to initialize the class in order to access it. It's value is shared across all instances of the object, so creating multiple DB class instances allows you tot just return a static if it was set in a previous DB class instance.
class db{
static $link;
static function connect(){
if(self::$link = mysqli_connect(....)){
return self::$link;
} else {
die('could not connect to db');
}
}
static function getcon(){
return isset(self::$link) ? self::$link : self::connect();
}
}
class Categories{
function GetCategory($cat){
$myQuery = "SELECT * FROM test GROUP BY $cat";
return mysqli_query(db::getcon(), $myQuery);
}
}
Create an object of the db class in the categories class. Then use that object to query the db accordingly. Also make sure you use a static variable in the db class. SO that the connection variable is created once and will be used all along the application.
Your db class may look like this
class db {
public $server = 'localhost';
public $user = '';
public $passwd = '******';
public $db = '';
public static $dbCon;
function __construct() {
$this->dbCon = mysqli_connect($this->server, $this->user, $this->passwd, $this->db);
}
function __destruct() {
mysqli_close($this->dbCon);
}
}
Your categories class may look like this
class Categories {
$connection=db::$dbCon;
if(!$connection){
$db=new db();
$connection=db::$dbCon;
}
function GetCategory($cat) {
$myQuery = "SELECT * FROM test GROUP BY $cat";
$results = mysqli_query($this->connection, $myQuery);
return $results;
}
}
Below is the solution to my question. I didn't have my class written wrong. I accidentally used a "die" function inside my master DB class that made all my queries fail. I was tracking down the wrong problem.
I hope you guys find this class example useful. It's clean, and very useful for wrapping SQL calls in a single location for multiple databases. By allowing the extension, you can track your calls much easier my var name.
class A extends DB {
protected $connection;
function __construct()
{
$this->db_host = "server.com:3327";
$this->db_name = "db_name_one";
$this->db_username = "root";
$this->db_password = 'pw';
// .. equals all the setup vars
parent::__construct();
}
}
class B extends DB {
function __construct()
{
$this->db_host = "server.com:3327";
$this->db_name = "db_name_two";
$this->db_username = "root";
$this->db_password = 'pw';
// .. equals all the setup vars
parent::__construct();
}
}
class DB {
function __construct()
{
$this->connect()
}
public function connect()
if (!$connection = # mysql_connect ($this->db_host,$this->db_username,$this->db_password,$this->second_flag))
die ('I cannot connect to the database because: ' . mysql_error());
if (!mysql_selectdb($this->db_name,$connection))
$this->showerror();
return $connection;
}
public function executeSQL($query)
{
$results = mysql_query($query,$this->connection);
if (!$results) {
die(...);
}
return $results;
}
}
$db1 = new A();
$db2 = new B();
$db1->executeSQL("select * from table");
I don't know if there's a legitimate reason to extend the DB class here. Unless those extending classes add something to the DB (e.g. they adapt it to a different database), then they have nothing to do with being a DB as such. Just because they use a DB doesn't mean they should extend one.
The simplest thing to do is: make one class that handles your database interaction. When you make a new instance of that class, it establishes a new connection to the database. This way you can have as many independent connections as you want. You then simply pass those instances to whoever needs them:
class DB {
protected $connection;
public function __construct() {
$this->connection = mysql_connect(..);
if (!$this->connection) {
throw new Exception(..);
}
}
..
}
class A {
protected $db;
public function __construct(DB $db) {
$this->db = $db;
}
..
}
$db = new DB;
$a = new A($db);
Hope you can help me with this one: i have two classes: Database and Users. The Database connects to the database using PDO (inside the constructor) and has functions to alter tables, insert data, etc. The Users class will handle login, as well add/remove users. However, the Users class needs to connect to the database. How can i do this?
There are several things you could do:
Globals
$db = new Database();
class Users
{
public function foo()
{
global $db;
$db->query();
}
}
Setting a static variable
$db = new Database();
class Model
{
static public $db;
}
Model::$db = $db;
class Users extends Model
{
public function foo()
{
self::$db->query();
}
}
Use a singleton
class Database
{
private static $instance;
private function __construct()
{
}
public static function instance()
{
return self::$instance ? self::$instance : self::$instance = new self();
}
}
class Users
{
public function foo()
{
Database::instance()->query();
// or $db = Database::instance(); $db->query();
}
}
The one thing you want to avoid is creating a new database connection per model or class.
Same way you normally would, but it might help to make the database a class property:
<?php
class Users
{
protected $_db;
public function __construct(Database $database = null)
{
if (!$database) {
$database = new Database;
}
$this->_db = $database;
}
public function addUser($username)
{
// Do stuff ...
$this->_db->insert($data);
}
}
Then you can use the User class like:
<?php
$users = new Users;
$users->addUser('joebob');
Simply add a reference to the database class instance into Users:
class Users {
var $database;
function __construct() {
$this->database = new Database();
}
};
Alternatively, if Database is a singleton, just reference it directly.
One way to do so would be to create ONE shared instance of the database class, then use it as a global variable wherever needed.
Start by creating the instance anywhere in your project, just make sure it is in global space (not inside another class or function).
$DB = new Database();
Then to access the shared database object, just use the $GLOBALS built-in array:
class User {
function __construct() {
$DB = &$GLOBALS['DB'];
// do something
$DB->callSomeMethod();
}
...
}
As pointed out by #Ryan, namespace collisions are possible using this strategy. The best middle path out would be to convert the Database class into a singleton. Then it would store its own instance (translation: ONE connection no matter what) which could be accessed via a Database::getInstance() method.
This is my Users class:
class Users {
private $data;
private $db;
public function __construct() {
$db = Database::getInstance('localhost', 'database', 'root', '123456');
}
public function __get($key) {
return $this->data[$key];
}
public function __set($key, $value) {
$this->data[$key] = $value;
}
public function test() {
foreach($this->db->query('table', '*', '', '', '', '', '0,5') as $value) {
$results .= $value['field1'] . "<br />";
}
return $results;
}
}
I'm new to PHP oop stuff.
I'm trying to create class database and call other classes from it. Am I doing it the right way?
class database:
class database extends mysqli {
private $classes = array();
public function __construct() {
parent::__construct('localhost', 'root', 'password', 'database');
if (mysqli_connect_error()) {
$this->error(mysqli_connect_errno(), mysqli_connect_error());
}
}
public function __call($class, $args) {
if (!isset($this->classes[$class])) {
$class = 'db_'.$class;
$this->classes[$class] = new $class();
}
return $this->classes[$class];
}
private function error($eNo, $eMsg) {
die ('MySQL error: ('.$eNo.': '.$eMsg);
}
}
class db_users:
class db_users extends database {
public function test() {
echo 'foo';
}
}
and how I'm using it
$db = new database();
$db->users()->test();
Is it the right way or should it be done another way?
Thank you.
You can do it that way, there's nothing wrong with that (I do something similar quite often). The only thing I would suggest is using exceptions instead of die (that way you can safely handle the error)...
protected function error($eNo, $eMsg, $extra = '') {
throw new Exception('MySQL error: ['.$eNo.'] '.$eMsg.': '.$extra);
}
Plus, I'd suggest overloading the query method as well
public function query($sql, $result_mode = MYSQLI_STORE_RESULT) {
$result = parent::query($sql, $result_mode);
if ($result === false) {
$this->error($this->errno, $this->errstr, $sql);
}
return $result;
}
I'd also suggest storing a copy of the $db object inside of the child class. So:
class db_users extends database {
protected $db = null;
public function __construct(Database $db) {
$this->db = $db;
}
public function test() {
echo 'foo';
}
}
Then, in __call:
if (!isset($this->classes[$class])) {
$class = 'db_'.$class;
$this->classes[$class] = new $class($this);
}
There is nothing wrong with this factory style for creating classes. I'd place a bit of exception handling in it.
My only other concern is extending database in your sub classes.
So I'd modify as follows:
public function __call($className, $args) {
if (!isset($this->classes[$class])) {
if(include_once('db_'.$class)) {
$class = 'db_'.$class;
$this->classes[$class] = new $class($this);
} else {
throw new Exception("Db class not found");
}
}
return $this->classes[$class];
}
And the users class as:
public class db_users {
private $db;
public __constructor($db) {
$this->db = $db;
}
public function test() {
return 'Foo';
}
}
I want to be able to make classes which extend the MySQLi class to perform all its SQL queries.
$mysql = new mysqli('localhost', 'root', 'password', 'database') or die('error connecting to the database');
I dont know how to do this without globalising the $mysql object to use in my other methods or classes.
class Blog {
public function comment() {
global $mysql;
//rest here
}
}
Any help would be appreciated.
Thanks.
I was working on something similar. I'm happy about this singleton class that encapsulates the database login.
<?php
class db extends mysqli
{
protected static $instance;
protected static $options = array();
private function __construct() {
$o = self::$options;
// turn of error reporting
mysqli_report(MYSQLI_REPORT_OFF);
// connect to database
#parent::__construct(isset($o['host']) ? $o['host'] : 'localhost',
isset($o['user']) ? $o['user'] : 'root',
isset($o['pass']) ? $o['pass'] : '',
isset($o['dbname']) ? $o['dbname'] : 'world',
isset($o['port']) ? $o['port'] : 3306,
isset($o['sock']) ? $o['sock'] : false );
// check if a connection established
if( mysqli_connect_errno() ) {
throw new exception(mysqli_connect_error(), mysqli_connect_errno());
}
}
public static function getInstance() {
if( !self::$instance ) {
self::$instance = new self();
}
return self::$instance;
}
public static function setOptions( array $opt ) {
self::$options = array_merge(self::$options, $opt);
}
public function query($query) {
if( !$this->real_query($query) ) {
throw new exception( $this->error, $this->errno );
}
$result = new mysqli_result($this);
return $result;
}
public function prepare($query) {
$stmt = new mysqli_stmt($this, $query);
return $stmt;
}
}
To use you can have something like this:
<?php
require "db.class.php";
$sql = db::getInstance();
$result = $sql->query("select * from city");
/* Fetch the results of the query */
while( $row = $result->fetch_assoc() ){
printf("%s (%s)\n", $row['Name'], $row['Population']);
}
?>
My suggestion is to create a Singleton DataAccess class, instantiate that class in a global config file and call it in your Blog class like $query = DataAccess::query("SELECT * FROM blog WHERE id = ".$id).
Look into the Singleton pattern, it's a pretty easy to understand designpattern. Perfect for this situation.
Your DataAccess class can have several methods like query, fetchAssoc, numRows, checkUniqueValue, transactionStart, transactionCommit, transactionRollback etc etc. Those function could also be setup as an Interface which gets implemented by the DataAccess class. That way you can easily extend your DataAccess class for multiple database management systems.
The above pretty much describes my DataAccess model.
You can use PHP's extends keyword just for any other class:
class MyCustomSql extends mysqli {
public function __construct($host, $user, $password, $database) {
parent::__construct($host, $user, $password, $database);
}
public function someOtherMethod() {
}
}
$sql = new MyCustomSql('localhost', 'root', 'password', 'database') or die('Cannot connect!');
or better use object aggregation instead of inheritance:
class MySqlManipulator {
private $db;
public function __construct($host, $user, $password, $database) {
$this->db = new mysqli($host, $user, $password, $database);
}
public function someOtherMethod() {
return $this->db->query("SELECT * FROM blah_blah");
}
}
$mysqlmanipulator = new MySqlManipulator('localhost', 'root', 'password', 'database') or die('Cannot connect!');
My standard method is to make a singleton class that acts as the database accessor, and a base class that everything requiring such access inherits from.
So:
class Base {
protected $db;
function __construct(){
$this->db= MyDBSingleton::get_link();
//any other "global" vars you might want
}
}
class myClass extends Base {
function __construct($var) {
parent::__construct();// runs Base constructor
$this->init($var);
}
function init($id) {
$id=(int) $id;
$this->db->query("SELECT * FROM mytable WHERE id=$id");
//etc.
}
}
Have a look at PDO, which throw exceptions for you to catch if a query fails. It's widely used and tested so you shouldn't have a problem finding existing solutions whilst using it.
To inject it into your blog class:
class Blog {
private $_db;
public function __construct(PDO $db) {
$this->_db = $db
}
public function comment() {
return $this->_db->query(/*something*/);
}
}