Seeders for http://blog.phakeapps.com/products-in-multilevel-categories-with-many-to-many-relation

CategoryProductSeeder.php

<?php

use Carbon\Carbon;
use Illuminate\Database\Seeder;
use Illuminate\Support\Facades\DB;

class CategoryProductTable extends Seeder
{
    /**
     * Run the database seeds.
     *
     * @return void
     */
    public function run()
    {
        $products = \App\Product::all();
        //Categories that don't have child categories.
        $categories = \App\Category::where('id', '!=', 'sub_category_id')->get();

        foreach ($products as $product) {
            DB::table('category_product')->insert([
                'category_id' => $categories->random()->id,
                'product_id' => $product->id,
                'created_at' => Carbon::now()->format('Y-m-d H:i:s')
            ]);
        }
    }
}

CategoryTableSeeder.php

<?php

use Carbon\Carbon;
use Illuminate\Database\Seeder;
use Illuminate\Support\Facades\DB;

class CategoryTableSeeder extends Seeder
{
    /**
     * Run the database seeds.
     *
     * @return void
     */
    public function run()
    {
        /**
         * We are going to insert 100 categories.
         */
        $faker = Faker\Factory::create();
        for ($i = 0; $i < 100; $i++) {
            DB::table('categories')->insert([
                'name' => implode($faker->words(),' '),
                'sub_category_id' => (($i % 2) === 0) ? $this->get_random_category_id() : null,
                'created_at' => Carbon::now()->format('Y-m-d H:i:s')
            ]);
        }
    }

    private function get_random_category_id()
    {
        $random_category = \App\Category::inRandomOrder()->first();
        return !is_null($random_category) ? $random_category->id : null;
    }
}

ProductTableSeeder.php

<?php

use Carbon\Carbon;
use Illuminate\Database\Seeder;
use Illuminate\Support\Facades\DB;

class ProductTableSeeder extends Seeder
{
    public function run()
    {
        /**
         * We are going to insert 500 products.
         */
        $faker = Faker\Factory::create();
        for ($i = 0; $i < 500; $i++) {
            DB::table('products')->insert([
                'name' => implode($faker->words(),' '),
                'description' => $faker->paragraph(),
                'price' => $this->mt_rand_float(0, 100),
                'created_at' => Carbon::now()->format('Y-m-d H:i:s')
            ]);
        }
    }

    //Thanks to: http://stackoverflow.com/a/38691102/867418
    private function mt_rand_float($min, $max, $countZero = '0')
    {
        $countZero = +('1' . $countZero);
        $min = floor($min * $countZero);
        $max = floor($max * $countZero);
        $rand = mt_rand($min, $max) / $countZero;
        return $rand;
    }
}