How to sort by nested laravel model?

Question

Laravel

There is a "Products" model, each product belongs to 1 category. How to get categories sorted by the number of products in a category through ActiveRecord in Laravel?
$category = Category::active()->orderBy([])->->paginate($per_page);

Answer 1

Use the sortBy() and count() collection methods.
Example:

$categories = Category::active->with('product')->get()->sortBy(function($category)
{
    return $category->product->count();
});