[NFR] Nested Set - pass custom parameters to search query OR implement user callback to modify DB queries

[temuri416]

Hi,

I need to be able to do something like this:

$children = $node->descendants([
    'approved' => 1,
]);

What do you think - maybe we need some sort of listener to pass the $query from here:

https://github.com/phalcon/incubator/blob/master/Library/Phalcon/Mvc/Model/Behavior/NestedSet.php#L206

And, to generalize it, call user method before each of the return $query->execute() that access the DB?

Thanks!

[temuri416]

Maybe what we really need is a support for Event Manager and observers.

[temuri416]

Something like this:

https://gist.github.com/temuri416/05b94d7e3491994993a997d150d32ea0#file-nestedset-php-L21

Example of use is at the bottom.

[Ultimater]

Very practical need to be able to grab descendants with an extra condition.

I believe the best solution here would be changing return $query->execute(); to return $query; in descendants based on the presence of a 3rd boolean parameter. Then you can extend NestedSet and easily modify the query by adding an extra WHERE clause before executing it.

[Ultimater]

A listener could work too. Depends on what people like working with.

[Ultimater]

I feel your pain that you'd expect a solution as readable as the code you posted:

$children = $node->descendants([
    'approved' => 1,
]);

But then we're forgetting about the optional parameters:

public function descendants($depth = null, $addSelf = false)

and you wind up with:

    $children = $node->descendants(null,false,[
        'approved' => 1,
    ]);

[temuri416]

Right, that's why implementing Events Manager is much cleaner.

[Ultimater]

What if we needed three kinds of queries: approved => 0, approved => 1, and an omitted version?
Then you're calling a method before descendants in order to toggle some sort of global state.

Searching is rather case specific and shouldn't be toggling a global state in my opinion.

I'd counter-suggest adding a new method.
Perhaps:

    $children = $node->descendantsBy([
        'approved' => 1,
    ]);

[temuri416]

My idea is that query modification is done by implementer:

$eventsManager = new EventsManager;
$eventsManager->attach(BehNestedSet::EVT_TYPE_QUERY, function(Event $event, Criteria $criteria, AbstractNode $node) {
    if ($callback = $node->getQueryModificationCallback()) {
        $callback($criteria);
    }
});

Here your $node that implements Nested Set behavior will contain the callback that will do anything it needs.

[temuri416]

1. I have also improved roots() method in my gist.
2. Perhaps another useful addition would be to fire cancelable events with 'modify:' prefix before tree modification takes place: append(), appendTo(), moveBefore() and so on.

[sergeysviridenko]

I propose close this issue

[sergeyklay]

Implemented in the latest stable release. Feel free to open a new issue if the problem appears again. Thank you for contributing!