lithium\data\entity\Document::offsetSet PHP Method

Allows document fields to be assigned as array keys, i.e. $document['_id'] = $id.

public offsetSet ( mixed $offset, mixed $value ) : void
$offset	mixed	String or integer indicating the offset or the name of a field in an individual document.
$value	mixed	The value to assign to the field.
return	void

    public function offsetSet($offset, $value)
    {
        return $this->set(array($offset => $value));
    }

Document