PHP - Static Factory Class Functions/dependency Injection/singletons

If a class has a constructor but also has a static method, if I call the static method does the constructor run so that I can use an output from the constructor in my static method?

--Kenoli

I write for example class Text:


class Text {
    public static function test() {
        return 'test text';
    }
}


Today I found this code:


class Text {
     
      /** 
       * Protected constructor since this is a static class.
       *
       * @access  protected
       */  
    protected function __construct(){
        // Nothing here
    }

    public static function test() {
        return 'test text';
    }
}


How much appropriate is to write this?


    /** 
       * Protected constructor since this is a static class.
       *
       * @access  protected
       */  
    protected function __construct(){
        // Nothing here
    }

I everyone, I'm developing a small MVC framework for my personal work, now, in order to have access from all the classes to certain variables I've created a registry class, for this to work I have 2 options:
1.- passing every time the registry object to the constructor class(controllers, models, etc)
or
2.- create in the registry static set and get so I can reach the variables by Registry::set(name, value) and Registry::get(name)

My question is, which one of this two options takes less resources(is faster)?

I hope anyone can help me with this, thanks in advance

heres an example of the code i have
Code: [Select]
class someclass
{

public function run($parm)
{
system($parm);
}

public static function create($item1,$item2)
{
$this->run($item1 . $item2);
}

}

then i have a file that attempts to use the create method:
someclass::create($one,$two);

when interpreting, i get this error: "Using $this when not in object context in"

does anyone know how I can fix this? I think I understand why its wrong (the class hasn't really been set up) - I just dont know how to correct it. Is there a way I can access class functions without using $this ? additionally I tried making the run method static too, but that didnt seem to work.

Is it ok to do this?
Code: [Select]
class Two {

 function anything() {
   classOne::anyMethod();
 }

}

I'm sure it is but this doesn't pose very well for if I wanted to swop out one class for another. I'd then have to make changes to the code (unless I were sure all classes were named the same).

--

What I want it for (and this may be another issue), is this:

I may need to create more than one database instance:
Code: [Select]
//Database exends mysqli
$db[1] = new Database(2);//database 2 used this time
$db[2] = new Database(5);//db5

I then always use Database::closeAll() at any point in my script to ensure all connections are closed. Of course $this->close wouldn't close all instances/connections, just the one I was working on.

I know I don;t have to close all connections, but I may as well, and there are other occasions where the first part of this question applies, so please don't just respond "no need to close".

Database::closeAll() is this:
Code: [Select]
public static function closeAll() {

//closes ALL active instances (not just this one)

global $db;

foreach($db as $v) {

$db[$v]->close(); unset($db[$v]);

}
        }

I have the following simple class:

Code: [Select]
class Settings {
  public static $mysql_datetime_format = "%c/%e/%Y %l:%i %p " . date("[T]");
}

And referencing like:

Code: [Select]
echo Settings::$mysql_datetime_format;

But, I am getting the error: Parse error: syntax error, unexpected '.', expecting ',' or ';'.

Why is this invalid?

I have 2 php files. I am unable to get B's global variable from A's static method:

A.php
Code: [Select]
class c_A
  { public static function f_A()
      { include_once( "B.php" ) ;
        print f_B() ;
      }
  }
c_A::f_A( ); // only prints "B : "

B.php
Code: [Select]
$gvs = "global variable from B" ;

function f_B()
  { return "B : " . $GLOBALS[ "gvs" ] ;
  }


any thoughts?


thanks,
Shannon

Hello, my first post here.

I created a Validation class that depends entirely on static methods. It appears to be working well, but perhaps I misunderstood exactly the purpose and the consequences of using static methods.

My class essentially looks like this:


class Validate
{
static public $errors  = array();
static public $valid   = array();

static public function Name($name)
{
if ($name != '')
{
self::$valid['name'] = $name;
return true;
}
                                else
                                {
                self::$errors['name'] = 'Name is empty';
                return false;
                                 }
}
}


Does this create any chance whatsoever for a collision of data from multiple users? I am beginning to think it does, simply because from what I have recently learned about static methods, theyr'e essentially global variables because they are not instantiated. If that's the case, then it would seem possible that during times of heavy use, any application depending on this class would confuse submitted data.

Any thoughts?

Thanks in advance.

Hi guys, I am trying something fairly simple but I'm not sure if this would be a good practice. Basically I am using a big class called CommonLibrary that holds common functions as methods and common variables as static variables. But I have some variables here and there like $allAlphabet = range ('a' , 'z'), that cannot be declared as a property because it gives me a parse error.

I don't want to call an object for this class because instancing it is of no use. Values will never change with regards to instances. So the next best thing that I tried was declaring all static variables first, and then changing thei property values inside the class __construct with self::$variable = 'somevalue', and then using this code below to assign values to the empty static variables.


$dummyObject = new CommonLibrary;
unset($dummyObject);
echo CommonLibrary::$staticVariable; // This property is NULL before the constructer is triggered.


Anyone recommend any better ways of doing this?

Thanks in advance!

Hi!

I have a class with many functions/methods. I want to split this into different files so I can easily edit and add functions.
I want every functions to be able to call eachother and with that I mean, they have to be for example in same document.

My question is: I can't have a class and include functions like this:

Code: [Select]
class DB
{

include('select_functions.php'); //Only includes function's no class
include('insert_functions.php'); //Only includes function's no class
include('delete_functions.php'); //Only includes function's no class

function test()
{

}

}
The includes will output fatal errors...

How can I solve this so I can have all functions in different files but still use ONE object to call them!

Thanks!

I think I need to use $this, but I need to be able to add the two values returned from both of my functions.  How would I do that?

Code: [Select]
public function get_users_edge($uid)
{
$users_primary->get_users_primary_edge($uid);
$users_dynamic->get_users_dynamic_edge($uid);

echo $users_primary + $users_dynamic;
}

hello

i have some normal php functions that i want to put into a oop class.

i cant seem to make the right changes to make it work. could some one help please. thanks

these are the php functions

Code: [Select]
<?php

  function hasChild($parent_id)
  {
    $sql = "SELECT COUNT(*) as count FROM category WHERE parent_id = '" . $parent_id . "'";
    $qry = mysql_query($sql);
    $rs = mysql_fetch_array($qry);
    return $rs['count'];
  }
  
  function CategoryTree($list,$parent,$append)
  {
    $list = '<li>'.$parent['name'].'</li>';
    
    if (hasChild($parent['id'])) // check if the id has a child
    {
      $append++;
      $list .= "<ul class='child child".$append."'>";
      $sql = "SELECT * FROM category WHERE parent_id = '" . $parent['id'] . "'";
      $qry = mysql_query($sql);
      $child = mysql_fetch_array($qry);
      do{
        $list .= CategoryTree($list,$child,$append);
      }while($child = mysql_fetch_array($qry));
      $list .= "</ul>";
    }
    return $list;
  }
  function CategoryList()
  {
    $list = "";
    
    $sql = "SELECT * FROM category WHERE (parent_id = 0 OR parent_id IS NULL)";
    $qry = mysql_query($sql);
    $parent = mysql_fetch_array($qry);
    $mainlist = "<ul class='parent'>";
    do{
      $mainlist .= CategoryTree($list,$parent,$append = 0);
    }while($parent = mysql_fetch_array($qry));
    $list .= "</ul>";
    return $mainlist;
  }
?>


this is the class


Code: [Select]
<?PHP
require_once(LIB_PATH.DS.'database.php');

class Menu extends DatabaseObject {

protected static $table_name="menu";

protected static $db_fields = array(
'id',
'parent_id',
'name'
);


public $id;
public $parent_id;
public $name;


// "new" is a reserved word so we use "make"(or "build")
public static function make(

$id,
$parent_id,
$name) {

if(!empty($id)) {

$kw = new Menu();
$kw->id = (int)$id;
$kw->parent_id = (int)$parent_id;
$kw->name = $name;

return $kw;
}else{
return false;
}
} //end function make


//PUT FUNCTIONS HERE......

  function hasChild($parent_id)
  {
    $sql = "SELECT COUNT(*) as count FROM category WHERE parent_id = '" . $parent_id . "'";
    $qry = mysql_query($sql);
    $rs = mysql_fetch_array($qry);
    return $rs['count'];
  }
 
  function CategoryTree($list,$parent,$append)
  {
    $list = '<li>'.$parent['name'].'</li>';
   
    if (hasChild($parent['id'])) // check if the id has a child
    {
      $append++;
      $list .= "<ul class='child child".$append."'>";
      $sql = "SELECT * FROM category WHERE parent_id = '" . $parent['id'] . "'";
      $qry = mysql_query($sql);
      $child = mysql_fetch_array($qry);
      do{
        $list .= CategoryTree($list,$child,$append);
      }while($child = mysql_fetch_array($qry));
      $list .= "</ul>";
    }
    return $list;
  }
  function CategoryList()
  {
    $list = "";
   
    $sql = "SELECT * FROM category WHERE (parent_id = 0 OR parent_id IS NULL)";
    $qry = mysql_query($sql);
    $parent = mysql_fetch_array($qry);
    $mainlist = "<ul class='parent'>";
    do{
      $mainlist .= CategoryTree($list,$parent,$append = 0);
    }while($parent = mysql_fetch_array($qry));
    $list .= "</ul>";
    return $mainlist;
  }
?>

Hi,    I'm struggling to understand how to load a PHP classes for my database into a php function.    My class in on another file, which is included into my page.    I then have a function that usings the class of $database->query in the function, but for some reason this doesn't work.    However the class works on the page outside of the function, is there someway I must load the class into my function?   Thanks for reading. 

Hi, I'm having a bit of a problem understanding why I'm not able to use the class I'm extending off of functions.

I have a category class that extends off my core class, inside that category class, I'm able to use the core functions and variables inside all custom functions, but not the __construct function.

So, to be clear, inside class class, I'm able to call $this->core->function() inside custom functions, such as function add_parent(), but not the __construct function.

Why is this happening, what is the logic behind this?

This is how I'm extending the class off of the core class:
Code: [Select]
<?php
$core  = new core;
$parent = new parents;
$parent->core =& $core;
?>

With this, like I said, I'm able to use all of my core functions inside all other classes called this way, so inside all of the other classes I can do:
Code: [Select]
<?php $this->core->function(); ?>everywhere besides __construct().

Do I not have the class called properly? Do I need to pass my core class through differently? How can I fix this?

Thanks.

I am currently building my own MVC Framework and I have run into an issue that I can't solve when attempting to use 2 methods from a single model. I know that this isn't an issue with the queries or information being return. I am unsure of the proper way that I can call 2 methods when checking to see if a user is logged in... The issue that I face is both methods are calling the DB and it throws a PDO error which I don't know how to get around the issue.. Any guidance would be nice as I have been banging my head over this issue. Thank you!

 

Fatal error: Uncaught Error: Call to undefined method PDO::Select() in C:\xampp\htdocs\PicWrist\app\models\user.class.php:318 Stack trace: #0 C:\xampp\htdocs\PicWrist\app\controllers\home.php(21): User->getUser('4') #1 C:\xampp\htdocs\PicWrist\app\core\app.php(36): Home->index() #2 C:\xampp\htdocs\PicWrist\app\init.php(47): App->__construct() #3 C:\xampp\htdocs\PicWrist\public\index.php(5): require('C:\\xampp\\htdocs...') #4 {main} thrown in C:\xampp\htdocs\PicWrist\app\models\user.class.php on line 318

 

//Controller

<?php 
	/**
	 * Load the View
	 */
	class Controller{

		public function view($view, $data = []) {
			if (file_exists('../app/views/' . $view . '.php')) {
				require_once '../app/views/' . $view . '.php';
			} 
		}

		public function model($model, $data = []) {

			if (file_exists('../app/models/' . $model . '.class.php')) {
				require_once '../app/models/' . $model . '.class.php';

				return new $model();

			} else 

				return false;
		}
	}

?>

//Home Controller
<?php 
Class Home extends Controller {

	public static $user;
	public $errors;

	public function __construct() {

		self::$user = $this->model('user');

	}

	public function index() {
		$userdata 			= [];
		$data				= [];

		show(self::$user);
		$isLoggedin	= self::$user->isLoggedin;
		show($isLoggedin);

		$userdata = self::$user->getUser($_SESSION['user_id']);
		show($userdata);

		$this->view('home', $data);
	}

}

?>
<?php 
/**
 * Users
 */
class User
{
	private $db;
	private $errors = '';
	public $isLoggedin = False;
	public $isAdmin = False;

	public function __construct() {
		$this->isLoggedIn();
	}

	public function isLoggedIn() {

		if(isset($_SESSION['user_id'])){

			$data['user_id'] = $_SESSION['user_id'];
			$db = Database::getInstance();
			$query = "SELECT * FROM users WHERE user_id = :user_id LIMIT 1";
			$results = $db->Select($query, $data);

			if (is_array($results)) {
				 $this->isLoggedIn = True;
			}
		}

	}


	public function getUser($id) {

		if(isset($id)) {

			$data['user_id']	= intval($id);
			$db 				= Database::getInstance();
			$query 				= 'SELECT * FROM users WHERE user_id = :user_id';

			$results = $db->Select($query, $data);

			if (is_array($results)) {
				return $results;
			} else {
				return False;
			}
		} else {
			return False;
		}
	}

//DB
<?php 
	/**
	 * Database Connection
	 */
	class Database	{
		private $dbHost = DB_HOST;
		private $dbUser = DB_USER;
		private $dbPass = DB_PASS;
		private $dbName = DB_NAME;

		private $statment;
		private static $dbHandler;
		private $error;

		public function __construct()
		{
			$conn = 'mysql:host=' . $this->dbHost . ';dbname=' . $this->dbName;

			$options = array(
				PDO::ATTR_PERSISTENT 	=> true,
				PDO::ATTR_ERRMODE 		=> PDO::ERRMODE_EXCEPTION
			);

			try {
				self::$dbHandler = new PDO($conn, $this->dbUser, $this->dbPass, $options);
			} catch (PDOException $e) {
				self::$error = $e->getMessage();
				echo self::$error;
			}
		}

		public static function getInstance() {

			if(self::$dbHandler) {
				return self::$dbHandler;
			}

			return $instance = new Self();
		}

		public function Select($query, $data = array()) {
			$statement = self::$dbHandler->prepare($query);
			$result	= $statement->execute($data);

			If($result) {
				$data = $statement->fetchAll(PDO::FETCH_OBJ);
					if(is_array($data)) {
						// show($data);
						return $data;
				}
			}

			return False;
		}

		public function Update($query, $data = array()) {
			$statement = self::$dbHandler->prepare($query);
			$result	= $statement->execute($data);

			If($result) {
				return True;
			} 
			
			return False;

		}

	}

?>

 

Edited July 14 by avargas94
Wrong Code