/**
* Builds a single string for the given scope columns values. Useful for
* making array keys for grouping.
*
* @param Tree\Node $node
* @return string
*/
protected function keyForScope($node)
{
return implode('-', array_map(function ($column) use($node) {
$value = $node->getAttribute($column);
if (is_null($value)) {
return 'NULL';
}
return $value;
}, $node->getScopedColumns()));
}
