In this tutorial, lets learn how to create a product attribute using data patches in Magento 2.

Data patch is a class that stores instructions for data modification. From Magento 2.3.x, magento introduced a new concept Data patch for add/update magento eav attributes. Previously, Magento 2 uses InstallData and UpgradeData file to use add data in core table or custom table. From Magento 2.3 it is replaced by Data Patch.

How to create product attribute using data patch in Magento 2 :

A data patch is a class that contains data modification instructions. It is defined in a <Vendor>/<Module_Name>/Setup/Patch/Data/<Patch_Name>.php file and implements \Magento\Framework\Setup\Patch\DataPatchInterface.

Data patches have three important methods:

• • getDependencies,
  • getAliases,
  • apply

Let’s understand the process of creating product attribute using data patches :

First of all, Let’s create simple module,

Create the module

Create the registration.php  file in app/code/Thecoachsmb/Productattribute/ for the module

<?php
\Magento\Framework\Component\ComponentRegistrar::register(
\Magento\Framework\Component\ComponentRegistrar::MODULE,
'Thecoachsmb_Productattribute',
__DIR__
);

Create directory app/code/Thecoachsmb/Productattribute/etc

Put this file in it : module.xml

<?xml version="1.0"?>
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:Module/etc/module.xsd">
    <module name="Thecoachsmb_Productattribute" setup_version="1.0.0">
        <sequence>
            <module name="Magento_Catalog"/>
        </sequence>
    </module>
</config>

Create Text Field Product Attribute

Now, To create custom product attribute Create ProductAttribute.php file at app/code/Thecoachsmb/Productattribute/Setup/Patch/Data/  and paste the below code :

<?php
/**
 * Copyright © Magento, Inc. All rights reserved.
 * See COPYING.txt for license details.
 */

declare (strict_types = 1);

namespace Thecoachsmb\Productattribute\Setup\Patch\Data;

use Magento\Eav\Model\Entity\Attribute\ScopedAttributeInterface;
use Magento\Eav\Setup\EavSetup;
use Magento\Eav\Setup\EavSetupFactory;
use Magento\Framework\Setup\ModuleDataSetupInterface;
use Magento\Framework\Setup\Patch\DataPatchInterface;

class ProductAttribute implements DataPatchInterface {

    /**
     * ModuleDataSetupInterface
     *
     * @var ModuleDataSetupInterface
     */
    private $moduleDataSetup;

    /**
     * EavSetupFactory
     *
     * @var EavSetupFactory
     */
    private $eavSetupFactory;

    /**
     * @param ModuleDataSetupInterface $moduleDataSetup
     * @param EavSetupFactory          $eavSetupFactory
     */
    public function __construct(
        ModuleDataSetupInterface $moduleDataSetup,
        EavSetupFactory $eavSetupFactory
    ) {
        $this->moduleDataSetup = $moduleDataSetup;
        $this->eavSetupFactory = $eavSetupFactory;
    }

    /**
     * {@inheritdoc}
     */
    public function apply() {
        /** @var EavSetup $eavSetup */
        $eavSetup = $this->eavSetupFactory->create(['setup' => $this->moduleDataSetup]);

        $eavSetup->addAttribute('catalog_product', 'display_on_homepage', [
            'type' => 'text',
            'backend' => '',
            'frontend' => '',
            'label' => 'Display on Home Page',
            'input' => 'text',
            'class' => '',
            'source' => '',
            'global' => ScopedAttributeInterface::SCOPE_GLOBAL,
            'visible' => true,
            'required' => false,
            'user_defined' => false,
            'default' => '',
            'searchable' => false,
            'filterable' => false,
            'comparable' => false,
            'visible_on_front' => false,
            'used_in_product_listing' => true,
            'unique' => false,
            'apply_to' => '',
        ]);
    }

    /**
     * {@inheritdoc}
     */
    public static function getDependencies() {
        return [];
    }

    /**
     * {@inheritdoc}
     */
    public function getAliases() {
        return [];
    }
}

Here, In this above file there are some new functions available in that file code. So, Let’s understand short details about the use of that functions.

apply() function :- is used to create or update our custom attribute. We need to create an instance of the EavSetupFactory, passing in our moduleDataSetup object, and add our attribute required configuration.

The getDependencies() function :- we can return an array of strings that contains class names of dependencies. This tells Magento to execute the “patches” we define here first, before our setup script. With the help of this function Magento controls the order of how patch scripts are executed.

getAliases() function :- defines aliases for the patch class. Sometimes, When you want to change the class name then it could possible using getAliases() function. If it does, then we should add old class name so, it’s not executed a second time.

getVersion() function :- will return a version of the patch. It’s an optional method.

If the database version number of the module is lower than the version specified in the file, the patch will execute.

Example:

Database Version: 1.0.0
File Version: 1.0.1
Result: 1.0.0 < 1.0.1, patch will execute!

If the database version number of the module is equal to or higher than the version specified in the file, the patch will not execute.

In Last, Now just execute this below command :

php bin/magento s:up && php bin/magento s:s:d -f && php bin/magento c:f

<?php

/**
 * Copyright © Magento, Inc. All rights reserved.
 * See COPYING.txt for license details.
 */

declare (strict_types = 1);

namespace Thecoachsmb\Productattribute\Setup\Patch\Data;
use Magento\Eav\Model\Entity\Attribute\ScopedAttributeInterface;
use Magento\Eav\Setup\EavSetup;
use Magento\Eav\Setup\EavSetupFactory;
use Magento\Framework\Setup\ModuleDataSetupInterface;
use Magento\Framework\Setup\Patch\DataPatchInterface;

class ProductAttriMulti implements DataPatchInterface {

    /**
     * ModuleDataSetupInterface
     *
     * @var ModuleDataSetupInterface
     */
    private $moduleDataSetup;

    /**
     * EavSetupFactory
     *
     * @var EavSetupFactory
     */
    private $eavSetupFactory;

    /**
     * @param ModuleDataSetupInterface $moduleDataSetup
     * @param EavSetupFactory          $eavSetupFactory
     */

    public function __construct(
        ModuleDataSetupInterface $moduleDataSetup,
        EavSetupFactory $eavSetupFactory
    ) {
        $this->moduleDataSetup = $moduleDataSetup;
        $this->eavSetupFactory = $eavSetupFactory;
    }

    /**
     * {@inheritdoc}
     */

    public function apply() {
        /** @var EavSetup $eavSetup */
        $eavSetup = $this->eavSetupFactory->create(['setup' => $this->moduleDataSetup]);

        $eavSetup->addAttribute('catalog_product', 'custom_multiselect', [
            'type' => 'text',
            'backend' => 'Magento\Eav\Model\Entity\Attribute\Backend\ArrayBackend',
            'frontend' => '',
            'label' => 'Custom Multi Select',
            'input' => 'multiselect',
            'option' => ['values' => [
                'Option 1',
                'Option 2',
                'Option 3',
                ],
            ],
            'unit' => '',
            'class' => '',
            'source' => '',
            'global' => ScopedAttributeInterface::SCOPE_GLOBAL,
            'visible' => true,
            'required' => true,
            'user_defined' => false,
            'default' => '',
            'searchable' => false,
            'filterable' => false,
            'comparable' => false,
            'visible_on_front' => false,
            'used_in_product_listing' => true,
            'unique' => false,
            'apply_to' => '',
        ]);
    }

    /**
     * {@inheritdoc}
     */
    public static function getDependencies() {
        return [];
    }

    /**
     * {@inheritdoc}
     */
    public function getAliases() {
        return [];
    }
}

   'option' => ['values' => [
               'Option 1',
               'Option 2',
               'Option 3',
           ],
       ],

php bin/magento s:up && php bin/magento s:s:d -f && php bin/magento c:f