Laravel belongsToMany

2016_10_21_214304_create_products_table.php

<?php
/*
 * database/migrations/2016_10_21_214304_create_products_table.php
 */

use Illuminate\Database\Schema\Blueprint;
use Illuminate\Database\Migrations\Migration;

class CreateProductsTable extends Migration
{
    /**
     * Run the migrations.
     *
     * @return void
     */
    public function up()
    {
        Schema::create('products', function (Blueprint $table) {
            $table->increments('id');

            $table->string('name');

            $table->timestamps();
        });
    }

    /**
     * Reverse the migrations.
     *
     * @return void
     */
    public function down()
    {
        Schema::drop('products');
    }
}

2016_10_21_214309_create_categories_table.php

<?php
/*
 * database/migrations/2016_10_21_214309_create_categories_table.php
 */

use Illuminate\Database\Schema\Blueprint;
use Illuminate\Database\Migrations\Migration;

class CreateCategoriesTable extends Migration
{
    /**
     * Run the migrations.
     *
     * @return void
     */
    public function up()
    {
        Schema::create('categories', function (Blueprint $table) {
            $table->increments('id');

            $table->string('name');

            $table->timestamps();
        });
    }

    /**
     * Reverse the migrations.
     *
     * @return void
     */
    public function down()
    {
        Schema::drop('categories');
    }
}

2016_10_21_214645_create_category_product_table.php

<?php
/*
 * database/migrations/2016_10_21_214645_create_category_product_table.php
 */

use Illuminate\Database\Schema\Blueprint;
use Illuminate\Database\Migrations\Migration;

class CreateCategoryProductTable extends Migration
{
    /**
     * Run the migrations.
     *
     * @return void
     */
    public function up()
    {
        Schema::create('category_product', function (Blueprint $table) {
            $table->integer('product_id')->unsigned();
            $table->integer('category_id')->unsigned();
        });
    }

    /**
     * Reverse the migrations.
     *
     * @return void
     */
    public function down()
    {
        Schema::drop('category_product');
    }
}

Category.php

<?php
/*
 * app/Category.php
 */

namespace App;

use Illuminate\Database\Eloquent\Model;

class Category extends Model
{

    public function products()
    {
        return $this->belongsToMany(Product::class);
    }

}

Product.php

<?php
/*
 * app/Product.php
 */

namespace App;

use Illuminate\Database\Eloquent\Model;

class Product extends Model
{

    public function categories()
    {
        return $this->belongsToMany(Category::class);
    }

}