Magento 2 – Custom pattern and error message for field validation in the admin panel

This article will help you to show how to add custom pattern and validation error message for a text field in the admin panel.

First, you need to create a category attribute using a module setup script and you can add validation on the XML file.

Add the setup script to create a category attribute in the following file.


namespace MilanDev\CustomField\Setup;

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

class InstallData implements InstallDataInterface

    private $eavSetupFactory;

     * Constructor
     * @param \Magento\Eav\Setup\EavSetupFactory $eavSetupFactory
    public function __construct(EavSetupFactory $eavSetupFactory)
        $this->eavSetupFactory = $eavSetupFactory;

     * {@inheritdoc}
    public function install(
        ModuleDataSetupInterface $setup,
        ModuleContextInterface $context
    ) {
        $eavSetup = $this->eavSetupFactory->create(['setup' => $setup]);

                'type' => 'varchar',
                'label' => 'My Custom Field',
                'input' => 'text',
                'sort_order' => 333,
                'source' => '',
                'global' => 1,
                'visible' => true,
                'required' => false,
                'user_defined' => false,
                'default' => null,
                'group' => 'General Information',
                'backend' => ''

Now, add the custom pattern and validation error message in the following.

<?xml version="1.0" ?>
<form xmlns:xsi="" xsi:noNamespaceSchemaLocation="urn:magento:module:Magento_Ui:etc/ui_configuration.xsd">
	<fieldset name="general">
		<field name="my_custom_field">
			<argument name="data" xsi:type="array">
				<item name="config" xsi:type="array">
					<item name="required" xsi:type="boolean">false</item>
					<item name="sortOrder" xsi:type="number">333</item>
					<item name="dataType" xsi:type="string">string</item>
					<item name="formElement" xsi:type="string">input</item>
					<item name="label" translate="true" xsi:type="string">My Custom Field</item>
					<item name="validation" xsi:type="array">
						<item name="required-entry" xsi:type="array">
							<item name="validate" xsi:type="boolean">true</item>
							<item name="message" xsi:type="string">Custom error message for required field.</item>
						<item name="pattern" xsi:type="array">
							<item name="validate" xsi:type="boolean">true</item>
							<item name="value" xsi:type="string">/^[A-Za-z]+[A-Za-z0-9_]+$/i</item>
							<item name="message" xsi:type="string">Custom error message for pattern validation</item>

After following the above steps you can input the wrong characters and check. You should see something in the screenshot.

Magento 2 – Customer pattern and error message in the admin panel.

I hope, these tips and tricks will help you. Happy Coding.

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