Can class default public variables be defined dynamically from an array in php?

Question

I have a event class that i am using to insert/update data into my database. Is there a way that i can create the public variables from my db_fields array so that i am not having to duplicate the data?

This is my current structure which works...

class event{
    protected static $table_name='tName';
    protected static $db_fields = array('field1','field2','field3','field4','field5');

    public $field1;
    public $field2;
    public $field3;
    public $field4;
    public $field5;
}

I would like to have something like this..

class event{
    protected static $table_name='tName';
    protected static $db_fields = array('field1','field2','field3','field4','field5');

    function __construct() {
        create_public_vars_here($db_fields);
    }

}

Thanks!

Answer 1

You can try the following:

class event{

    protected static $table_name='tName';
    protected static $db_fields = array('field1','field2','field3','field4','field5');

    function __construct() {
        foreach (self::$db_fields as $var) {
            $this->$var = $whateverDefaultValue;
        }
        // After the foreach loop, you'll have a bunch of properties of this object with the variable names being the string values of the $db_fiels.
        // For example, you'll have $field1, $field2, etc and they will be loaded with the value $whateverDefaultValue (probably want to set it to null).
    }

}

Answer 2

You can use magic setters / getters:

class event{

    protected static $table_name='tName';
    protected static $db_fields = array('field1','field2','field3','field4','field5');

    public function __get($key)
    {

        if(!in_array($key, static::$db_fields))
            throw new Exception( $key . " doesn't exist.");

        return $this -> $key;

    }

    public function __set($key, $value)
    {

        if(!in_array($key, static::$db_fields))
            throw new Exception( $key . " doesn't exist.");

        $this -> $key = $value;

    }   

}

This way you are sure not to hit values outside your list:

$event -> field1 = 'hello';  // --> OK
$event -> field17 = 'hello'; // --> Exception: field17 doesn't exist

echo $event -> field1;  // --> OK
echo $event -> field17; // --> Exception: field17 doesn't exist

As for having an explicit public variable declaration in your code, you have no need as long as you don't have to iterate over your objects - but in this case you'd implement Iterator interface based on your static field.

Answer 3

Use mutators:

class event{
  protected static $table_name='tName';
  protected static $db_fields = array('field1','field2','field3','field4','field5');

  function getVars($var) {
    if(!in_arrary($this->db_fields[$var])) {
      return false;
    } else {
      return $this->db_fields[$var];
    }
  }
}

And then you can access it like this:

$eventObject->getVars('field3');

Or, if you don't create an object out of the class:

event::getVars('field3');

EDIT: In the spirit of complicating things so that you don't have a bounds violation, code added.