How can I set custom validation using controller in system config file in Magento 2?

Question

I want to set custom validation on system config file that "accept character do not allow any script tag" only accept like that

ex. config/group/field, config/group/field

enter image description here

Here is my system.xml file

<?xml version="1.0"?>
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:module:Magento_Config:etc/system_file.xsd">
 <system>
 <tab id="ccc" translate="label" sortOrder="10">
 <label>Ccc</label>
 </tab>
 <section id="secureconfig" translate="label" sortOrder="130" showInDefault="1" showInWebsite="1" showInStore="1">
 <class>separator-top</class>
 <label>SecureConfig</label>
 <tab>ccc</tab>
 <resource>Ccc_SecureConfig::secure_config</resource>
 <group id="general" translate="label" type="text" sortOrder="10" showInDefault="1" showInWebsite="0" showInStore="0">
 <label>General Configuration</label>
 <field id="enable" translate="label" type="select" sortOrder="1" showInDefault="1" showInWebsite="0" showInStore="0">
 <label>Module Enable</label>
 <source_model>Magento\Config\Model\Config\Source\Yesno</source_model>
 </field>
 <field id="config_path" translate="label" type="textarea" sortOrder="1" showInDefault="1" showInWebsite="0" showInStore="0">
 <label>Config Path </label>
 <comment>Add Config Path with , seprator Like (config/group/field, config/group/field)</comment>
 <validate>required-entry validate-data</validate>
 </field>
 </group>
 </section>
 </system>
</config>

• Waqar Ali: see this magecomp.com/blog/…
• Jay Parmar: that only for lenght , i need validation as = accept character do not allow any script tag , like config/group/field, config/group/field
• Waqar Ali: yopu have to add regex

Answer 1

try below code

<field id="config_path" translate="label" type="textarea" sortOrder="1" showInDefault="1" showInWebsite="0" showInStore="0">
 <label>Config Path </label>
 <comment>Add Config Path with , seprator Like (config/group/field, config/group/field)</comment>
 <frontend_class>validate-alpha</frontend_class>
</field>

for validation, you need to add like this

<frontend_class>validate-alpha</frontend_class>

validate-alpha -- > Character only

validate-number -- > Number Only

required-entry --> required field