DMZ 1.7.1 (DataMapper OverZealous Edition)

[eluser]OverZealous[/eluser]
@Skipper
This isn't specifically related to DMZ, but try the magic __get method: it's used throughout DMZ to handle relationships and more.

Code:

// in *your* class
public function __get($field) {
    if($field == 'inventoryvalue') {
        return $this->quantity_on_stock * $this->cost_per_unit;
    }
    // important: defer to DMZ!
    return parent::__get($field);
}

Then you can access it like a field.

Code:

echo $object->inventoryvalue;

If you reference the value a lot, you may want to cache it, by setting $this->inventoryvalue to the result of the multiplication. (The magic __get method is only called if the field does not already exist on the object.)

One more thing: If you want the field to show up in your IDE (assuming you use one), put this in the class's PHPDoc comment:

Code:

/**
* ...
*
* @param float $inventoryvalue
*/
class MyClass extends DataMapper {
...