Question

In PHP, I have a product object that contains a collection of attributes. json_encode produces this:

{"id":"123","name":"abc","attributes":{"attributes":[{"key":"sku","value":"xyz"}]}}

“attributes” listed twice is redundant. What’s the best way of structuring object collections so that the json is clean?

class Product {

    public $id;
    public $name;
    public $attributes;

    public function __construct()
    {
        $this->attributes = new Attributes();
    }

    public function get($id)
    {
        $this->id = "123";
        $this->name = "abc";
        $attribute = new Attribute("sku", "xyz");
        $this->attributes->add($attribute);
    }
}

class Attributes
{
    public $attributes;

    public function __construct()
    {
        $this->attributes = array();
    }

    public function add($attribute)
    {
        array_push($this->attributes, $attribute);
    }
}

class Attribute
{
    public $key;
    public $value;

    public function __construct($key, $value)
    {
        $this->set($key, $value);
    }
}

Answer 1

I would just use an associative array.

class Product {
...
    public $attributes=array();
    ...
    public function get($id)
    {
        ...
        $this->attributes["sku"]="xyz";
        $this->attributes["foo"]="bar";
    }
}

json_encode() should produce something like this:

{"id":"123","name":"abc","attributes":{"sku":"xyz","foo":"bar"}}

OR using variable variables:

class Attributes
{
    public function add($key,$value)
    {
        $this->{$key}=$value;
    }
    public function drop($key)
    {
        unset($this->{$key});
    }
}

$a=new Attributes();
$a->add('sku','xyz');
$a->add('foo','bar');
echo json_encode($a).'<br>';
$a->drop('sku');
echo json_encode($a).'<br>';

Output:

{"sku":"xyz","foo":"bar"}
{"foo":"bar"}