PHP - Php Class Question

I created a database class to connect to a database.  The code is below.  I'm not sure how to call this connection in other classes.  Do I use:

$db->pdo = $conn->prepare($sql);

or what?  Note that the db object is instantiated at the end of the class file.  Here is the class:

 

class DB {
	
	public $pdo = '';
	//public $message = 'A message from db'; // Debug

function __construct() {
	
	// Database info located elsewhere
	$servername = "localhost";
	$username = "root";
	$password = "";
	$dbname = "dbname";
	
	try {
		
	  $this->pdo = new PDO("mysql:host=$servername;dbname=$dbname", $username, $password);
	  // set the PDO error mode to exception
	  $this->pdo->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);

	}  // End Try
	
	catch(PDOException $e) {
		  echo "Error: " . $e->getMessage();
		}
		
		//echo '<h3>Everything wnet OK.</h3>';  // Debug

	} // End __construct
	
} // End class definition DB.php

$db = new DB;

Thanks,

 

--Kenoli

I'm confused as to why assigning these variables in the class causes the page not to load...


var $RootFolder = '/shyid/';
var $PagePath = str_replace($this->RootFolder, '', dirname($_SERVER['PHP_SELF']));
var $PageSections = explode('/', $this->PagePath);


but when i set them on the page, everything works correctly?


$head->RootFolder = '/shyid/';
$head->PagePath = str_replace($head->RootFolder, '', dirname($_SERVER['PHP_SELF']));
$head->PageSections = explode('/', $head->PagePath);


Insight? Thanks.

Imagine 6 PHP classes (one each for a product line), that have very similar coding structures, that go like this:

//function that computes stuff inside each of 6 files:
//they vary slightly from file to file but essentially it is this:
function computeFunction
{
    $this->x = new X();

    $this->x->calcD();

    if ($this->x->dOk)
    {
        $this->x->calcE();
        $this->x->calcN();   
    }

    //more complicated logic that is essentially like above

    //and by the way!
    print $this->x->someVarThatIsUsedLater;
}

Then there is a single class like so :

class X
{
    function calcD()
    {
        //compute some condition

        if (<computed condition is met>) $this->dOk = true;
        else $this->dOk = false;

        //and by the way
        $this->someVarThatIsUsedLater = 4;
    }
}

Just to bring your attention to it, none of these functions return any result or value, but they nevertheless operate on variables of key interest via side-effects.  That is, they modify variables that essentially act like globals, and then use those variables later ($this->dOk and $this->someVarThatIsUsedLater are one more prominent examples).   I need to untangle this mess.  And make it clean and clear again, and make sense.  How do I best proceed?   I have been wrestling with some ideas... like $this->dOk, can within reason be turned into a return variable of calcD() function, and then be tested against like if ($this->x->calcD()) and I think it will be reasonable enough.  But then there are other functions that don't return anything and just act on variables via side-effects anyway so $this->dOk is one of the lesser troubles...   Other than that, what I am thinking of doing is getting rid of these mini-functions (calcE(),  calcN(), etc.), removing them as a funciton, and putting their body directly into the code, as a first step to refactor.  Many of the computations done inside are just a few lines of code anyway, and the functions kind of hide a lot of side-effects that happen, instead of actually encapsulating the behavior.  So while it may be counter-intuitive to dismantle the functions that appear to be doing something that normally can be encapsulated (computing key variables E, N, etc), I think dismantling them will actually clean things up as far as collecting all the side-effects inside a single parent function thereby making them more visible.   Caveat:  while doing so I will end up with 6 copies of untangled dismantled functions, because dismantling class X and putting its content into each of the 6 product line classes will have that effect.   But my hope is that from that point I will see more clearly to start identifying places where I can start to truly encapsulating the behavior via various structures, instead of masking it.   Problems / Questions: I would like to but I am not entirely sure that I can skip that step of dismantling functions & the 6x multiplying effect. It's probably the same like skipping steps in solving polynomial equations.  Some can do it and some need to list each step of their work. And I am not entirely sure what structures I can replace it with in the end after I dismantle the functions. It also looks like a lot of work.  Is there a better way? P.S. I already put tests on computeFunction() for each product line so I can be less paranoid about hacking stuff up.
Edited by dennis-fedco, 19 January 2015 - 03:06 PM.

I have mysqli object in Database class base:

[color=]database class:[/color]

class Database {
  private $dbLink = null;
  
  public function __construct() {
    if (is_null($this->dbLink)) {
      // load db information  to connect
      $init_array = parse_ini_file("../init.ini.inc", true);
      $this->dbLink = new mysqli($init_array['database']['host'],
                           $init_array['database']['usr'],
                           $init_array['database']['pwd'],
                           $init_array['database']['db']);
  
      if (mysqli_connect_errno()) {
        $this->dbLink = null;
      }
    }
  }

  public function __destruct() {
    $this->dbLink->close();
  }
}


Class derived is Articles where I use object dBLink in base (or parent) class and I can't access to mysqli methods (dbLink member of base class):

Articles class:

require_once ('./includes/db.inc');

class Articles extends Database{
  private $id,
              ....
              ....
             $visible = null;
  
  public function __construct() {
    // Set date as 2009-07-08 07:35:00
    $this->lastUpdDate = date('Y-m-d H:i:s');
    $this->creationDate = date('Y-m-d H:i:s');
  }
  
  // Setter
  ....
  ....

  // Getter
  ....
  ....

  public function getArticlesByPosition($numArticles) {
    if ($result = $this->dbLink->query('SELECT * FROM articles ORDER BY position LIMIT '.$numArticles)) {
      $i = 0;
      while ($ret = $result->fetch_array(MYSQLI_ASSOC)) {
        $arts[$i] = $ret;
      }
      $result->close();
      return $arts;
    }
  }
}


In my front page php I use article class:


include_once('./includes/articles.inc');
$articlesObj = new articles();
$articles = $articlesObj->getArticlesByPosition(1);
var_dump($articles);


[color=]Error that go out is follow[/color]

Notice: Undefined property: Articles::$dbLink in articles.inc  on line 89

Fatal error: Call to a member function query() on a non-object in articles.inc on line 89

If I remove constructor on derived class Articles result don't change 
Please help me

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

Ok. I know you can pass the object of a class as an argument. Example:


class A {
    function test() {
        echo "This is TEST from class A";
    }
}


class B {
    function __construct( $obj ) {
        $this->a = $obj;
    }

    function test() {
       $this->a->test();
    }

}


Then you could do:

$a = new A();
$b = new B($a);


Ok so that's one way i know of.

I also thought that you could make a method static, and do this: (assuming class A's test is 'static')

class B {
    function test() {
       A::test(); 
   }
}


But that is not working.


I'd like to know all possible ways of accomplishing this. Any hints are appreciated. thanks

I have an existing instance of my class Database, now I want to call that instance in my Session class, how would I go about doing this?

Hi

Can you call Class A's methods or properties from Class B's methods?

Thanks.

Hi,

I need to be able to call a class based on variables.  E.G.

I would normally do:
Code: [Select]
$action = new pattern1()
but i would like to be able to do it dynamicaly:
Code: [Select]
$patNum = 1;
$action = new pattern.$patNum.()
Im wondering if that's possible?  If so what would the correct syntax be?

Many Thanks.

I have two classes:

## Admin.php

<?php
class Admin
{
public function __construct()
{
include("Config.php");
}

/**
* deletes a client
* @returns true or false
*/
function deleteClient($id)
{
return mysql_query("DELETE FROM usernames WHERE id = '$id'");
}
}
?>


## Projects.php

<?php
class Projects
{
public function __construct()
{
include("Config.php");
$this->admin = $admin;
$this->dataFolder = $dataFolder;
}

/**
* Deletes a project
* @returns true or false
*/
function deleteProject($id)
{
$root  = $_SERVER['DOCUMENT_ROOT'];
$theDir  = $root . $this->dataFolder;
$sql  = mysql_query("SELECT * FROM projectData WHERE proj_id = '$id'");
while ($row = mysql_fetch_array($sql))
{
$mainFile = $row['path'];
$thumb = $row['thumbnail'];
if ($thumb != 'null')
{
unlink($theDir . "/" . substr($thumb,13));
}
unlink($theDir . "/" . substr($mainFile,13));
}
$delete = mysql_query("DELETE FROM projectData WHERE proj_id = '$id'");
$getDir = mysql_query("SELECT proj_path FROM projects WHERE id = '$id'");
$res = mysql_fetch_array($getDir);
rmdir($theDir . "/" . $res['proj_path']);
return mysql_query("DELETE FROM projects WHERE id = '$id'");
}
}
?>


How can I call deleteProject() from within Admin.php?

Hi people!

class FirstOne{

public function FunctionOne($FirstInput){
//do stuff and output value
return $value1;
}

}


Then:-


class SecondOne{

public function FunctionTwo($AnotherInput){
//do stuff and output value
return $value2;
}

}


What I want to know is this, if I want to use FunctionOne() in Class SecondOne do I do it like this:-

(Assume as I have instantiated the first class using $Test = new FirstOne(); )


class SecondOne{

function SecondedFunction(){
global $Test;
return $Test->FunctionOne();
}

public function FunctionTwo($AnotherInput){
//do stuff and output value
return $value2;
}

public function FunctionThree(){

//some code here
$this->Test->SecondedFunction();<--I think as I can omit the $this-> reference
}
}


My point is: Do I have to do it this way or is there way of having this done through __construct() that would negate the need for a third party function?

I have a version working, I just think that it is a little convoluted in the way as I have done it, so I thought I would ask you guys.

Any help/advice is appreciated.

Cheers
Rw

I do know how to do this but I am curious about whether or not there is a "preferred" way to do this. I know there are a couple ways to use a class (I'll call Alpha_Class) within another class (I'll class Beta_Class)

Let's say we have this simple class (Beta_Class):

class beta {
    function foo(){
    
    }
}


If I wanted to use the Alpha Class within the Beta Class, I could any number of things. For example:

class beta {
    function foo(){
        $this->alpha = new alpha;
        //$this->alpha->bar();
    }
}


Or you could simply use the $GLOBALS array to store instantiated objects in:

$GLOBALS['alpha'] = new alpha;
class beta {
    function foo(){
        //GLOBALS['alpha']->bar();
    }
}


You could even declare Alpha_Class as a static class and thus would not need to be instantiated:

static class alpha {
    static function bar(){}
}

class beta {
    function foo(){
        //alpha::bar();
    }
}


Those are the only ways I can think of right now. Are there any other ways to accomplish this? I was wondering which way is the best in terms of readability and maintainability.

How does one go about using one class inside another?

For example, building a class that does some series of functions, and uses a db abstraction layer class in the process?

I have a class in which I have a function called connection. I am now trying to call this function from another class, but it will not work. It works if I put the code in from the other function rather than calling it but that defeats the purpous.

class locationbox

{
   function location()
   {
   
   
   $databaseconnect = new databaseconnect();
         $databaseconnect -> connection();{

$result = mysql_query("SELECT * FROM locations");

while($row = mysql_fetch_array($result)) // line that now gets the error, mysql_fetch_array() expects parameter 1 to be resource, boolean given //in
  {
  echo "<option>" . $row['location'] . "</option>";
    }
   
}
}}

Hi all,

I have two classes. Registration and Connection.

Inside a registration.php I include my header.php, which then includes my connection.php...

So all the classes should be declared when the page is loaded.

This is my code:


registration.php:

<?php include ('assets/header.php'); ?> 
        
    <?php
        class registration{                    
            public $fields = array("username", "email", "password");
            public $data = array();
            public $table = "users";
            public $dateTime = "";
            public $datePos = 0;
            public $dateEntryName = "date";
            
            function timeStamp(){
                return($this->dateTime = date("Y-m-d H:i:s"));
            }
            
            function insertRow($data, $table){      
                    
                    foreach($this->fields as $key => $value){
                        mysql_query("INSERT INTO graphs ($this->fields)
                        VALUES ('$data[$key]')");
                    }
                    
                    mysql_close($connection->connect);
            }
            
            function validateFields(){
            
                $connection = new connection(); 
                $connection->connect();
                        
                foreach($this->fields as $key => $value){
                    array_push($this->data, $_POST[$this->fields[$key]]);
                }
                $this->dateTime = $this->timeStamp();
                array_unshift($this->data, $this->dateTime);                
                array_unshift($this->fields, $this->dateEntryName);   
                
                foreach($this->data as $value){
                    echo "$value";
                }
                
                $this->insertRow($this->data, $this->table);
            }
        }
        
        $registration = new registration();
        $registration->validateFields();
    ?>

<?php include ('assets/footer.php'); ?>



At this point I cannot find my connection class defined on another included/included page.



                $connection = new connection(); 
                $connection->connect;





config.php (included within header.php)

<?
    class connection{ 
        public $dbname = '**';   
        public $dbHost = '**';
        public $dbUser = '**';
        public $dbPass = '**';
        public $connect;
        
        function connect(){
            $this->connect = mysql_connect($this->dbHost, $this->dbUser, $this->dbPass) or die ('Error connecting to mysql');
            mysql_select_db($this->dbname, $this->connect);
        }
    }
?>



Any ideas how to call it properly?