Recursively generating heading numbers

For the Mijn Koepelkerk project I needed to create a page that would show all the organizational information like key figures, statutes, official stances on specific topics, and so forth. Each item is either a root item or a child item. The child items can have child items themselves. This is a recursive structure, which meant I could easily generate header numbers and depth.

    /**
     * The heading number including super-items. E.g.: "1.1".
     */
    protected function headingNumber(): Attribute
    {
        return Attribute::get(fn(): string => !$this->parent
            ? "$this->sort_index"
            : "{$this->parent->heading_number}.{$this->sort_index}"
        );
    }

    /**
     * How many levels this item is, starting at 1.
     */
    protected function depth(): Attribute
    {
        return Attribute::get(fn(): int => 1 + ($this->parent?->depth ?? 0));
    }

This makes use of Laravel’s attribute accessors to create computed properties, which can then be accessed like any other property.

Reflection

A WYSIWYG¹ editor like CKEditor could have been a less complex option, with the downside that if you want to make any change in the structure of the page, you were going to have to re-number all the headings manually, as I don’t know of any easily integrated WYSIWYG editors that support auto numbering of headings.