1. Under your Magento 2 module > inside the directory “Setup”
   (Create Magento 2 Module, Magento 2 install scripts)
   Create a new file: “UpgradeData.php” with the below content.

   
   <?php
   namespace Magleaks\Catalog\Setup;
   
   use Magento\Catalog\Model\Product;
   use Magento\Eav\Setup\EavSetupFactory;
   use Magento\Framework\Setup\ModuleContextInterface;
   use Magento\Framework\Setup\ModuleDataSetupInterface;
   use Magento\Framework\Setup\UpgradeDataInterface;
   
   class UpgradeData implements UpgradeDataInterface
   {
       /**
        * EAV setup factory
        *
        * @var EavSetupFactory
        */
       private $eavSetupFactory;
   
       /**
        * Init
        *
        * @param EavSetupFactory $eavSetupFactory
        */
       public function __construct(EavSetupFactory $eavSetupFactory)
       {
           $this->eavSetupFactory = $eavSetupFactory;
       }
   
       /**
        * @param ModuleDataSetupInterface $setup
        * @param ModuleContextInterface   $context
        */
       public function upgrade(
           ModuleDataSetupInterface $setup,
           ModuleContextInterface $context
       ) {
           $dbVersion = $context->getVersion();
           /** @var EavSetup $eavSetup */
           $eavSetup = $this->eavSetupFactory->create(['setup' => $setup]);
   
           if (version_compare($dbVersion, '2.0.1', '<')) { // update an existing product attribute to add as soring options
               $eavSetup->updateAttribute(
                   Product::ENTITY,
                   'name',
                   'used_for_sort_by',
                   false
               );
           }
       }
   }
   
   

2. Update the setup_version of your module in “etc/module.xml” file in your Module.

   
   <config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="../../../../../lib/internal/Magento/Framework/Module/etc/module.xsd">
       <module name="Magleaks_Catalog" setup_version="2.0.1"/>
   </config>
   
   

3. Go to your Magento 2 root folder from your terminal and run

   
   bin/magento setup:upgrade
   

1. Under your Magento 2 module, create a directory called “Setup”. (Create Magento 2 Module)
2. Create a new file: “InstallData.php” inside the Setup directory with the below content.

   
   <?php
   namespace Magleaks\Catalog\Setup;
   
   use Magento\Catalog\Model\Product;
   use Magento\Catalog\Model\Product\Type;
   use Magento\Catalog\Model\Resource\Eav\Attribute;
   use Magento\Eav\Setup\EavSetupFactory;
   use Magento\Framework\Setup\InstallDataInterface;
   use Magento\Framework\Setup\ModuleContextInterface;
   use Magento\Framework\Setup\ModuleDataSetupInterface;
   
   /**
    * Class InstallData
    *
    * @package Magleaks\Catalog\Setup
    */
   class InstallData implements InstallDataInterface
   {
       /**
        * @var \Magento\Eav\Setup\EavSetupFactory
        */
       private $eavSetupFactory;
       /**
        * @param EavSetupFactory $eavSetupFactory
        */
       public function __construct(EavSetupFactory $eavSetupFactory)
       {
           $this->eavSetupFactory = $eavSetupFactory;
       }
       /**
        * @param ModuleDataSetupInterface $setup
        * @param ModuleContextInterface   $context
        */
       public function install(ModuleDataSetupInterface $setup, ModuleContextInterface $context)
       {
           /** @var EavSetup $eavSetup */
           $eavSetup = $this->eavSetupFactory->create(['setup' => $setup]);
           $productTypes = [
               Type::TYPE_SIMPLE,
               Type::TYPE_VIRTUAL,
           ];
           $productTypes = join(',', $productTypes);
           $eavSetup->addAttribute(
               Product::ENTITY,
               'on_sale',
               [
                   'type'                    => 'int',
                   'label'                   => 'Sale',
                   'input'                   => 'boolean',
                   'sort_order'              => 50,
                   'global'                  => Attribute::SCOPE_WEBSITE,
                   'user_defined'            => true,
                   'required'                => false,
                   'used_in_product_listing' => true,
                   'apply_to'                => $productTypes,
                   'group'                   => 'General',
                   'unique'                  => false,
                   'visible_on_front'        => false,
                   'searchable'              => false,
                   'filterable'              => false,
                   'comparable'              => false,
                   'visible'                 => true,
                   'backend'                 => '',
                   'frontend'                => '',
                   'class'                   => '',
                   'source'                  => '',
                   'default'                 => '',
               ]
           );
       }
   }
   
   

3. Go to your Magento 2 root folder from your terminal and run

   
   bin/magento setup:upgrade
   

Magento 2 introduced brand new theme management mechanism. Some of new features are as follows

• Extending layout files. In Magento 1 we had to copy entire layout xml file to local folder in order to make any changes. But Magento to allow it to extend layout files. Just need copy the part that you want to change. Also it allow you to override entire layout xml as in Magento 1, but it is not recommended.
• Organized layout structure. Does not allow to add layout files without module folder. Check the folder structure.
• Less as css compiler.
• Css / Less inheritance. Less files from parent theme can be changed in custom themes.

• Built in less compiler to make development easier.
• Css/Less library.

I will be demonstrating how to create and apply new theme in Magento 2 in part 2.

Part 2