Cakephp 3 - get fields and conditions in beforefind - cakephp

Question

In cakephp 2.x in beforeFind I could check if some condition is set by
!empty($queryData['conditions'][$this->alias.'.field']) or get the list of fields that would be retrived simply by $queryData['fields']. How to achieve this in cakephp 3.x ?
In beforeFind
public function beforeFind(Event $event, Query $query, $options, $primary)
{
}
the options is empty. The $query I can use to add conditions by $query->where(...), but how to check what fields are set to be retrieved or what conditions are already applied ?
Thanks

Answer 1

Taken from the CakePHP 3.0 API documentation:
traverse( callable $visitor , array $parts [] )
Will iterate over every specified part. Traversing functions can aggregate results using variables in the closure or instance variables. This function is commonly used as a way for traversing all query parts that are going to be used for constructing a query.
The callback will receive 2 parameters, the first one is the value of the query part that is being iterated and the second the name of such part.
Example:
$query->select(['title'])->from('articles')->traverse(function ($value, $clause) {
if ($clause === 'select') {
var_dump($value);
}
}, ['select', 'from']);
So just call $query->traverse() and provide the callback closure and do your checks inside of it. See also traverseExpressions().

Answer 2

Thanks for the hint, but method "traverse" in the 4th version I already did not work like this.
I looked at it in the Cake core:
public function beforeFind($event, $query, $options, $primary)
{
$query
->clause('where')
->iterateParts(function ($callable) use (&$params): void {
if ($callable->getField() === 'url') {
// do something
}
$params[] = [
$callable->getField() . ' ' . $callable->getOperator() => $callable->getValue()
];
});
$query->where($params);
}