Admin System Configuration

Complete system.xml

<?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>
        <section id="vendor_prep" type="text" sortOrder="300" showInDefault="1" showInWebsite="1" showInStore="0">
            <label>Vendor Prep</label>
            <tab>general</tab>
            <group id="general" type="text" sortOrder="10" showInDefault="1" showInWebsite="1" showInStore="1">
                <label>General Settings</label>
                <field id="enabled" type="select" sortOrder="10" showInDefault="1" showInWebsite="1" showInStore="0">
                    <label>Enable Module</label>
                    <source_model>Magento\Config\Model\Config\Source\Yesno</source_model>
                </field>
                <field id="title" type="text" sortOrder="20" showInDefault="1" showInWebsite="1" showInStore="1">
                    <label>Module Title</label>
                    <validate>required-entry</validate>
                </field>
            </group>
            <group id="api" type="text" sortOrder="20" showInDefault="1" showInWebsite="0" showInStore="0">
                <label>API Settings</label>
                <field id="api_url" type="text" sortOrder="10" showInDefault="1" showInWebsite="0" showInStore="0">
                    <label>API URL</label>
                    <validate>required-entry validate-url</validate>
                </field>
                <field id="api_key" type="obscure" sortOrder="20" showInDefault="1" showInWebsite="0" showInStore="0">
                    <label>API Key</label>
                    <backend_model>Magento\Config\Model\Config\Backend\Obfuscate</backend_model>
                </field>
            </group>
        </section>
    </system>
</config>

Field Types

menu.xml

<?xml version="1.0"?>
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
        xsi:noNamespaceSchemaLocation="urn:magento:module:Magento_Backend:etc/menu.xsd">
    <menu>
        <!-- Add to existing menu -->
        <add id="Amazon_Prep::prep"
             title="Prep Manager"
             module="Amazon_Prep"
             sortOrder="200
             resource="Amazon_Prep::prep"/>

        <!-- Add child items -->
        <add id="Amazon_Prep::prep_warranties"
             title="Warranties"
             module="Amazon_Prep"
             sortOrder="10"
             parent="Amazon_Prep::prep"
             resource="Amazon_Prep::warranties"/>

        <add id="Amazon_Prep::prep_settings"
             title="Settings"
             module="Amazon_Prep"
             sortOrder="20"
             parent="Magento_Backend::stores"
             action="adminhtml/system_config/edit/section/vendor_prep"
             resource="Amazon_Prep::settings"/>
    </menu>
</config>

Menu Item Attributes

Adding to Existing Menu

<!-- Add under Sales menu -->
<add id="Amazon_Prep::warranties"
     title="Warranties"
     module="Amazon_Prep"
     sortOrder="100"
     parent="Magento_Sales::sales Operations"
     resource="Amazon_Prep::warranties"/>

Custom Source Model

<?php
namespace Amazon\Prep\Model\Config\Source;

class WarrantyType implements \Magento\Framework\Option\ArrayInterface
{
    public function toOptionArray(): array
    {
        return [
            ['value' => 'standard', 'label' => __('Standard')],
            ['value' => 'extended', 'label' => __('Extended')],
            ['value' => 'premium', 'label' => __('Premium')],
        ];
    }
}

Use in system.xml:

<field id="warranty_type" type="select" sortOrder="10" showInDefault="1">
    <label>Warranty Type</label>
    <source_model>Amazon\Prep\Model\Config\Source\WarrantyType</source_model>
</field>

Backend Model

<?php
namespace Amazon\Prep\Model\Config\Backend;

class WarrantyDuration extends \Magento\Config\Model\Config\Backend\AbstractBackend
{
    public function afterSave(): void
    {
        $value = $this->getValue();
        if ($value < 1 || $value > 120) {
            throw new \Magento\Framework\Exception\LocalizedException(
                __('Duration must be between 1 and 120 months')
            );
        }
    }

    public function afterLoad(): void
    {
        // Process value after loading from database
    }
}

Use in system.xml:

<field id="warranty_duration" type="text" sortOrder="20" showInDefault="1">
    <label>Duration (months)</label>
    <validate>validate-digits validate-range range-1-120</validate>
    <backend_model>Amazon\Prep\Model\Config\Backend\WarrantyDuration</backend_model>
</field>

Backend Model Methods

ScopeConfigInterface

<?php
namespace Amazon\Prep\Service;

use Magento\Framework\App\Config\ScopeConfigInterface;
use Magento\Store\Model\ScopeInterface;

class ConfigService
{
    public function __construct(
        private ScopeConfigInterface $scopeConfig
    ) {}

    public function isEnabled(): bool
    {
        return (bool)$this->scopeConfig->getValue(
            'vendor_prep/general/enabled',
            ScopeInterface::SCOPE_STORE
        );
    }

    public function getTitle(): string
    {
        return $this->scopeConfig->getValue(
            'vendor_prep/general/title',
            ScopeInterface::SCOPE_STORE
        ) ?? 'Default Title';
    }

    public function getApiUrl(): string
    {
        return $this->scopeConfig->getValue(
            'vendor_prep/api/api_url',
            ScopeInterface::SCOPE_STORE
        );
    }
}

Configuration Path Format

section/group/field

Example: vendor_prep/general/enabled
         ^^^^^^^ ^^^^^^^^ ^^^^^^^
         section  group    field

Access in Block/Template

// In block class
public function isEnabled(): bool
{
    return (bool)$this->_scopeConfig->getValue(
        'vendor_prep/general/enited'
    );
}

// In template
$isEnabled = $block->isEnabled();

Access in Layout XML

<block class="..." name="...">
    <arguments>
        <argument name="enabled" xsi:type="object">
            Magento\Framework\App\Config\ScopeConfigInterface
        </argument>
    </arguments>
</block>

XMLPath to Scope Config

// Get all config values for a section
$sectionConfig = $this->scopeConfig->getValue('vendor_prep');

// Get nested value
$apiUrl = $sectionConfig['api']['api_url'];

// With default value
$value = $this->scopeConfig->getValue(
    'vendor_prep/general/title',
    ScopeInterface::SCOPE_STORE,
    $storeId
) ?? 'Default';