SilverStripe Weight Field

Weight.php

<?php

class Weight extends Decimal{


	function Nice(){
		//return in format appropriate to value eg 2grams instead of 0.002kg
	}

}

WeightField.php

<?php

class WeightField extends TextField{
	
	static $baseunit = 'kilogram';
	
	//rounding?
	
	static $unittable = array(
		'kilogram' => array(
					'convert' => 1,
					'abbreviation' => 'kg'
				),
		'gram' => array(
					'convert' => 0.001,
					'abbreviation' => 'g'
				),
		'pound' => array(
					'convert' => 0.45359237,
					'abbreviation' => 'lb'
				),
		'ounce' => array(
					'convert' => 0.0283495231,
					'abbreviation' => 'oz'
				)
	);
	
	
	function __construct($name, $title = null, $value = "", $form = null) {
		// naming with underscores to prevent values from actually being saved somewhere
		$this->fieldValue = parent::Field($name."[Amount]",$title,$value,$form);
		$this->fieldUnit = $this->UnitField($name);
		parent::__construct($name, $title, $value, $form);
	}
	
	function Field() {
		return "<div class=\"fieldgroup\">" .
				"<div class=\"fieldgroupField\">" . $this->fieldValue . "</div>" .
				"<div class=\"fieldgroupField\">" . $this->fieldUnit . "</div>" .
				"</div>";
	}
	
	function UnitField($name){
		
		$unittypes = array(
			'kilogram'
		);
		
		return new DropdownField("{$name}[Unit]",_t('WeightField.FIELDLABELUNIT', 'Unit'),$unittypes);
		
	}
	
}