[RESOLVED] ISSUE:calling properties from a object within an array

[numerical25]

I am creating a application that takes a product class that has properties such as (name, description and price) and putting the class within an array.

My issue is:: Im having problems calling the properties from the object within the array. Does anyone know how to go about storing an object within an array and calling it once its needed. here is my code

these are the functions im calling

$insert = new product_config();
$insert->set_product('candy','tasty','9.99');
$insert->render_products();
$insert->test();

when i call the render_products() function or test() function i get a error similar to this

Notice: Undefined variable: storage in C:\Program Files\EasyPHP 2.0b1\www\testing\product_config.php on line 24

Fatal error: Cannot access empty property in C:\Program Files\EasyPHP 2.0b1\www\testing\product_config.php on line 24

Below is the code that is ran once the functions is called

<?php 
	class product {
		private $product_name;
		private $description;
		private $price;

	public function _construct($name, $desc, $price){
		$this->product_name = $name;
		$this->description = $desc;
		$this->price = $price;
		echo $this->price;
	}
}

class product_config extends product {
	private $storage = array();

	function set_product($name, $desc, $price) {
		$this->storage[] = $new_product = new product($name, $desc, $price); 
	}

	function test(){

/*Here i was echoing hello jus to see if anything works */

		echo 'hello';

/*the function works til it reaches below, then It doesnt work. I get this error
Notice: Undefined variable: storage in C:\Program Files\EasyPHP 2.0b1\www\testing\product_config.php on line 24 */


		echo $this->$storage[0]->product_name;
	}		

	function render_products(){
		if (!$storage){
			return 'There are no products in storage!';
		}
		else{
			foreach ($storage as $value){
				echo $value->product_name."</br>";
			}
		}
	}
	}

?>

[dagon]

as error says the storage var in product_config.php is undefined

[NogDog]

One problem is that you misspelled __construct in the product class (it starts with 2 underscores). However, once you fix that, you'll then have a problem unless you overwrite it in your product_config class, since you apparently do not want to supply the parameters to its constructor like you do to its parent class.

PS: In the render_products() method, you'll need to refer to $this->storage rather than just $storage in both places. Then you'll have an error in the echo statement since product_name is private, so you'll either need to make a "get" type method in product to retrieve it, or else make the variable public.

[numerical25]

I could make the name protected too can i ??

[numerical25]

ok here is the new code

<?php
class product {
protected $product_name;
protected $description;
protected $price;

	public function __construct($name, $desc, $price){
		echo $name;
		$this->product_name = $name;
		$this->description = $desc;
		$this->price = $price;
		return $this;
	}
}

class product_config extends product {
	private $storage = array();

	function set_product($name, $desc, $price) {
		return $this->storage[] = new product($name, $desc, $price); 
	}

	function test(){
		return $this->storage[0]->product_name;
	}		

	function render_products(){
		if (!$this->storage){
			return 'There are no products in storage!';
		}
		else{
			foreach ($this->storage as $value){
				echo $value->product_name."</br>";
			}
		}
	}
	}

?>

Here is the functions being called
<? php
$insert = new product_config();
$insert->set_product('candy','tasty','9.99');
echo $insert->test();
?>

and here is the errors im getting

Warning: Missing argument 1 for product::__construct(), called in C:\Program Files\EasyPHP 2.0b1\www\testing\test_page.php on line 24 and defined in C:\Program Files\EasyPHP 2.0b1\www\testing\product_config.php on line 7

Warning: Missing argument 2 for product::__construct(), called in C:\Program Files\EasyPHP 2.0b1\www\testing\test_page.php on line 24 and defined in C:\Program Files\EasyPHP 2.0b1\www\testing\product_config.php on line 7

Warning: Missing argument 3 for product::__construct(), called in C:\Program Files\EasyPHP 2.0b1\www\testing\test_page.php on line 24 and defined in C:\Program Files\EasyPHP 2.0b1\www\testing\product_config.php on line 7

Notice: Undefined variable: name in C:\Program Files\EasyPHP 2.0b1\www\testing\product_config.php on line 8

Notice: Undefined variable: name in C:\Program Files\EasyPHP 2.0b1\www\testing\product_config.php on line 9

"However, once you fix that, you'll then have a problem unless you overwrite it in your product_config class, since you apparently do not want to supply the parameters to its constructor like you do to its parent class."

Notice: Undefined variable: desc in C:\Program Files\EasyPHP 2.0b1\www\testing\product_config.php on line 10

Notice: Undefined variable: price in C:\Program Files\EasyPHP 2.0b1\www\testing\product_config.php on line 11

It appears that my varibles arent getting passed over. I did change the constuct to 2 underscores instead of 1. Im not sure what you mean by this NogDog

[NogDog]

numerical25 wrote:

I could make the name protected too can i ??

Protected will throw the same error as private. The only difference is that a protected variable is visible to child classes that extend it, but you are referencing a separate object that was passed into the class, which has nothing to do with an extended parent/child relationship.

[NogDog]

Here's a version that works. Hopefully it actually does something along the lines of what you want it do do?

<?php
class product
{
   private $product_name;
   private $description;
   private $price;

   public function __construct($name, $desc, $price)
   {
      $this->product_name = $name;
      $this->description = $desc;
      $this->price = $price;
   }

   public function get_product_name()
   {
      return $this->product_name;
   }
}

class product_config extends product
{
   private $storage = array();

   // overwrite the parent's constructor
   public function __construct()
   {

   }

   function set_product($name, $desc, $price)
   {
      $this->storage[] = new product($name, $desc, $price);
   }

   function test()
   {
      echo $this->storage[0]->get_product_name();
   }

   function render_products()
   {
      if(!$this->storage)
      {
         return 'There are no products in storage!';
      }
      else
      {
         foreach($this->storage as $value)
         {
            echo $value->get_product_name() . "</br>";
         }
      }
   }
}

// TEST:
$insert = new product_config();
$insert->set_product('candy','tasty','9.99');
$insert->render_products();
$insert->test();
?> 

[numerical25]

So I had to overwrite the parents construct in order for the parents construct parameters to work in the child class ???

The only way I can get an object to work within a child class is to overwrite the constructor ??

Do you know of any articles that talks about this this type of code writing and why you have to overwrite the constructor ?

It is working and it is doing what its suppose to do. thanks nogdog.

[NogDog]

The reason I had to overwrite the constructor is that, since it is a public method in the parent class, the child class automatically inherits it. The parent class's constructor requires 3 parameters, but since you apparently did not want the child class to use those parameters, I had to overwrite it with, in this case, a do-nothing constructor with no parameters.

Without understanding the underlying purpose of these classes, I can't really say if this is the best way to do it. It might be that you want an abstract class with no constructor, then have both your product and product_config classes extend that abstract class, rather than product_config extending product. Or for that matter, perhaps they should simply be two separate classes if they're not actually sharing any attributes or functions?

As far as articles, you might want to check out this tutorial by Matt Zandstra. I haven't looked at it closely, but I really liked his book [/i]PHP 5 Objects, Patterns, and Practice[/i], so hopefully it's of similar quality and usefulness.