public function castValue($field, $value, $cast = true)
    {
        if (! array_key_exists($field, $this->casts) || ! $cast)
            // no cast configured for said field. Nothing done.
            return $value;

        $types = [
            "boolean", "bool", "integer", "int", "float", "double",
            "string", "array", "object", "null"
        ];

        // validate type cast is valid
        $type = $this->casts[$field];
        if (! in_array($type, $types)) {
            throw new RuntimeException("Cast of field '" . $field . "' to type '" . $type . "' not possible. Please define only scalar type casts.");
        }

        $output = $value;
        $result = settype($output, $type);

        if ($result === true)
            return $output;

        return $value;
    }