Dynamic loading of yii\bootstrap\Collapse widget content?

Question

Yii

I decided to display a "tree" list on YII2 using the yii\bootstrap\Collapse widget, since it collapses inactive branches by itself. The data is loaded from the database, the branching can be quite strong, and most importantly, the user in most cases will not view them at all, so I want to dynamically load the data to minimize the load on the server.

I hardly know JS and AJAX, I have already partially studied YII2, and it seems to me that somehow you can do everything with its means. Only the documentation shows how to dynamically replace data in views (PJAX), and I need to influence the content of the widget, respectively, and the html markup will change :)

That is, initially the following structure is rendered to the user:

Collapse::widget([
        'items' => [
            [
                'label' => 'Список 1',
                'content' => [],
            ],
            [
                'label' => 'Список 2',
                'content' => [],
            ],
        ]
    ]);

If you click on a list, then instead of an empty array, an array with real data should be loaded (including nested Collapse widgets, which can also be expanded without restrictions on nesting depth).
It seems to be a standard task, but I don’t understand how to replace an empty array with one containing something, while not affecting the already generated parts of the view?

Answer 1

first question: why did you decide that this option is less resource-intensive compared to building a full tree? Hiding child elements in Collapse. If the result of building a tree (html) is cached, this will be correct.
Now on the question:
after the Collapse widget has worked, you already have html, and arrays have nothing to do with it explicitly. Then we forget about php and work with jquery. You need to hook on the shown.bs.collapse event and send an ajax request to the server, form html there and return it, then insert it into the container.
bootstrap-3.ru/javascript.php#collapse