Laravel collection macros

AppServiceProvider.php

<?php

# app/Providers/AppServiceProvider.php

namespace App\Providers;

use Illuminate\Support\ServiceProvider;

class AppServiceProvider extends ServiceProvider
{
    /**
     * Bootstrap any application services.
     *
     * @return void
     */
    public function boot()
    {
        //

        require base_path('macros/collection.php');
    }

    /**
     * Register any application services.
     *
     * @return void
     */
    public function register()
    {
        //
    }
}

collection.php

<?php

# macros/collection.php

use Illuminate\Support\Collection;

if (! Collection::hasMacro('toHierarchy')) {
    /*
     * Get the collection of items as a hierarchical array.
     *
     * @param  string  $foreign
     * @param  string  $primary
     * @param  mixed  $value
     * @return \Illuminate\Support\Collection
     */
    Collection::macro('toHierarchy', function ($foreign = 'parent_id', $primary = 'id', $value = null) {
        return $this->where($foreign, $value)
                    ->map(function ($parent) use ($foreign, $primary) {
                        return data_set($parent, 'children', $this->toHierarchy(
                            $foreign, $primary, data_get($parent, $primary)
                        ));
                    })
                    ->values();
    });
}

web.php

<?php

# routes/web.php

use App\Category;

Route::get('/', function () {
    return Category::get()->sortBy('position')->toHierarchy();
});


/*
  Category table structure
  ---
  id
  parent_id
  title
  position
  created_at
  updated_at
*/