Magento2 – How to Create Category Attribute Programmatically

We need to identify the id of category tree root. Then, we created an instance of the category, set its path, parent_id, name, etc.

/**
 * Id of category tree root
 */
$parentId = \Magento\Catalog\Model\Category::TREE_ROOT_ID;

$parentCategory = $this->_objectManager
                      ->create('Magento\Catalog\Model\Category')
                      ->load($parentId);
$category = $this->_objectManager
                ->create('Magento\Catalog\Model\Category');
//Check exist category
$cate = $category->getCollection()
            ->addAttributeToFilter('name','test')
            ->getFirstItem();

if(!isset($cate->getId())) {
    $category->setPath($parentCategory->getPath())
        ->setParentId($parentId)
        ->setName('test')
        ->setIsActive(true);
    $category->save();
}

From Magento 2.1 and upper Version, You can also refer blog for create attribute programmatically in detais by, Create Custom category attribute in Magento 2

You have to just below code inside

For Magento Version 2.1.*

app/code/{Packagename}/{Modulename}/Setup/InstallData.php

<?php
namespace {Packagename}\{Modulename}\Setup;

use Magento\Framework\Setup\InstallDataInterface;
use Magento\Framework\Setup\ModuleContextInterface;
use Magento\Framework\Setup\ModuleDataSetupInterface;
use Magento\Catalog\Setup\CategorySetupFactory; 

class InstallData implements InstallDataInterface
{
    /**
    * Category setup factory
    *
    * @var CategorySetupFactory
    */
    private $categorySetupFactory;
    /**
    * Init
    *
    * @param CategorySetupFactory $categorySetupFactory
    */
    public function __construct(CategorySetupFactory $categorySetupFactory)
    {
         $this->categorySetupFactory = $categorySetupFactory;
    }

    public function install(ModuleDataSetupInterface $setup, ModuleContextInterface $context)
    {
         $installer = $setup;
         $installer->startSetup();
         $categorySetup = $this->categorySetupFactory->create(['setup' => $setup]);
         $entityTypeId = $categorySetup->getEntityTypeId(\Magento\Catalog\Model\Category::ENTITY);
         $attributeSetId = $categorySetup->getDefaultAttributeSetId($entityTypeId);

         $categorySetup->addAttribute(
         \Magento\Catalog\Model\Category::ENTITY, 'custom_attribute', [
            'type' => 'varchar',
            'label' => 'Custom Attribute Description',
            'input' => 'textarea',
            'required' => false,
            'sort_order' => 100,
            'global' => \Magento\Eav\Model\Entity\Attribute\ScopedAttributeInterface::SCOPE_STORE,
            'group' => 'General Information',
            'is_used_in_grid' => true,
            'is_visible_in_grid' => false,
            'is_filterable_in_grid' => true,
         ]
         );
         $installer->endSetup();
    }
}

app/code/{Packagename}/{Modulename}/view/adminhtml/ui_component/category_form.xml

<?xml version="1.0" encoding="UTF-8"?>
<form xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
      xsi:noNamespaceSchemaLocation="urn:magento:module:Magento_Ui:etc/ui_configuration.xsd">
  <fieldset name="general"> 
     <field name="custom_attribute">
        <argument name="data" xsi:type="array">
                <item name="config" xsi:type="array">
                    <item name="sortOrder" xsi:type="number">50</item>
                    <item name="dataType" xsi:type="string">string</item>
                    <item name="formElement" xsi:type="string">input</item>
                    <item name="label" xsi:type="string" translate="true">Custom Attribute Name</item>
                </item>
        </argument>
    </field>  
  </fieldset>
</form>

This is older version of Magento,

For Magento Version 2.0.*

Set category attribute like below,

app/code/Vendor/Categoryattr/Setup/InstallData.php file,

<?php
/**
 * Copyright © 2015 Magento. All rights reserved.
 * See COPYING.txt for license details.
 */

namespace Vendor\CategoryAttribute\Setup;

use Magento\Eav\Setup\EavSetup;
use Magento\Eav\Setup\EavSetupFactory;
use Magento\Framework\Setup\InstallDataInterface;
use Magento\Framework\Setup\ModuleContextInterface;
use Magento\Framework\Setup\ModuleDataSetupInterface;


class InstallData implements InstallDataInterface
{
    private $eavSetupFactory; 
    /**
     * Init
     *
     * @param EavSetupFactory $eavSetupFactory
     */
    public function __construct(EavSetupFactory $eavSetupFactory)
    {
        $this->eavSetupFactory = $eavSetupFactory;
    }

    /**
     * {@inheritdoc}
     * @SuppressWarnings(PHPMD.ExcessiveMethodLength)
     */
    public function install(ModuleDataSetupInterface $setup, ModuleContextInterface $context)
    {
        /** @var EavSetup $eavSetup */
        $eavSetup = $this->eavSetupFactory->create(['setup' => $setup]);
        /**
         * Add attributes to the eav/attribute
         */ 
        $eavSetup->addAttribute(
            \Magento\Catalog\Model\Category::ENTITY,
            'custom_attribute',
                      [
                        'type' => 'varchar',
                        'label' => 'Custom Attribute Description',
                        'input' => 'textarea',
                        'required' => false,
                        'sort_order' => 100,
                        'global' => \Magento\Eav\Model\Entity\Attribute\ScopedAttributeInterface::SCOPE_STORE,
                        'group' => 'General Information',
                        'is_used_in_grid' => true,
                        'is_visible_in_grid' => false,
                        'is_filterable_in_grid' => true,
            ]
        );


    }
}

remove var/generation folder and run command,

php bin/magento setup:upgrade to working inside category.