Magento 2 dynamic admin config

Question

I'm working on a custom module. I need a admin config section with dynamic options. The idea is to have a list of all enabled shipping methods. Next to each method i need a select dropdown with shipping methods loaded from an external system. How can create an admin config section with dynamic data?

Ive created an screenshot to clear things up on what i need:

I need a row for each enabled magento shipping method, and a dropdown next to it.

Answer 1

Try with below way.

Magento\Config\Block\System\Config\Form\Field\FieldArray\AbstractFieldArray class and override the _prepareToRender method in order to add columns to dynamic fields block, change “add button” label etc.

<?php

namespace Namespace\Modulename\Block\Adminhtml\Form\Field;

use Magento\Config\Block\System\Config\Form\Field\FieldArray\AbstractFieldArray;

/**
 * Class AdditionalEmail
 */
class AdditionalEmail extends AbstractFieldArray
{
    /**
     * {@inheritdoc}
     */
    protected function _prepareToRender()
    {
        $this->addColumn('firstname', ['label' => __('First Name'), 'class' => 'required-entry']);
        $this->addColumn('lastname', ['label' => __('Last Name')]);
        $this->addColumn('email',['label' => __('Email'), 'size' => '50px', 'class' => 'required-entry validate-email']);
        $this->_addAfter = false;
        $this->_addButtonLabel = __('Add Email');
    }
}

The data is saved in one record of the core_config_data table in the database for each system configuration field. That’s why we need to serialize the data before saving and unserialize this value back after loading.

<?php

namespace Namespace\Modulename\Config\Backend;

use Magento\Framework\App\Cache\TypeListInterface;
use Magento\Framework\App\Config\ScopeConfigInterface;
use Magento\Framework\App\Config\Value as ConfigValue;
use Magento\Framework\Data\Collection\AbstractDb;
use Magento\Framework\Model\Context;
use Magento\Framework\Model\ResourceModel\AbstractResource;
use Magento\Framework\Registry;
use Magento\Framework\Serialize\SerializerInterface;

/**
 * Class AdditionalEmail
 */
class AdditionalEmail extends ConfigValue
{
    /**
     * Json Serializer
     *
     * @var SerializerInterface
     */
    protected $serializer;

    /**
     * ShippingMethods constructor
     *
     * @param SerializerInterface $serializer
     * @param Context $context
     * @param Registry $registry
     * @param ScopeConfigInterface $config
     * @param TypeListInterface $cacheTypeList
     * @param AbstractResource|null $resource
     * @param AbstractDb|null $resourceCollection
     * @param array $data
     */
    public function __construct(
        SerializerInterface $serializer,
        Context $context,
        Registry $registry,
        ScopeConfigInterface $config,
        TypeListInterface $cacheTypeList,
        AbstractResource $resource = null,
        AbstractDb $resourceCollection = null,
        array $data = []
    ) {
        $this->serializer = $serializer;
        parent::__construct($context, $registry, $config, $cacheTypeList, $resource, $resourceCollection, $data);
    }

    /**
     * Prepare data before save
     *
     * @return void
     */
    public function beforeSave()
    {
        /** @var array $value */
        $value = $this->getValue();
        unset($value['__empty']);
        $encodedValue = $this->serializer->serialize($value);

        $this->setValue($encodedValue);
    }

    /**
     * Process data after load
     *
     * @return void
     */
    protected function _afterLoad()
    {
        /** @var string $value */
        $value = $this->getValue();
        $decodedValue = $this->serializer->unserialize($value);

        $this->setValue($decodedValue);
    }
}

etc/adminhtml/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="sample" translate="label" sortOrder="50">
            <label>Sample</label>
        </tab>
        <section id="test_sample" translate="label" type="text" sortOrder="10" showInDefault="1" showInWebsite="1" showInStore="1">
            <class>separator-top</class>
            <label>Test Sample</label>
            <tab>sample</tab>
            <resource>Namespace_Modulename::dynamic_fields</resource>
            <group id="additional" translate="label" type="text" sortOrder="10" showInDefault="1" showInWebsite="1" showInStore="1">
                <label>Additional</label>
                <field id="emails" translate="label" sortOrder="10" showInDefault="1" showInWebsite="1" showInStore="1">
                    <label>Additional Emails</label>
                    <frontend_model>Namespace\Modulename\Block\Adminhtml\Form\Field\AdditionalEmail</frontend_model>
                    <backend_model>Namespace\Modulename\Config\Backend\AdditionalEmail</backend_model>
                </field>
            </group>
        </section>
    </system>
</config>

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I hope it helps!