Drop down select list for custom Magento system configuration section

Question

I need to select one value from multiple options using a drop down select list in a custom system config file.

How should I write the config file?

Answer 1

Try this code.

system.xml

<field id="list_mode" translate="label" type="select" sortOrder="1" showInDefault="1" showInWebsite="1" showInStore="1">
   <label>List Mode</label>        
   <source_model>Vendor\Module\Model\Config\Source\ListMode</source_model>
</field>

Vendor\Module\Model\Config\Source\ListMode.php

namespace Vendor\Module\Model\Config\Source;

class ListMode implements \Magento\Framework\Data\OptionSourceInterface
{
 public function toOptionArray()
 {
  return [
    ['value' => 'grid', 'label' => __('Grid Only')],
    ['value' => 'list', 'label' => __('List Only')],
    ['value' => 'grid-list', 'label' => __('Grid (default) / List')],
    ['value' => 'list-grid', 'label' => __('List (default) / Grid')]
  ];
 }
}

Answer 2

As Magento\Framework\Option\ArrayInterface has been deprecated since v.102.0.1, I'm posting it in the current standard adopted by Magento (I'm using 2.3.3 and PHP 7.3):

<?php

namespace Vendor\Package\Model\Config\Source;

use Magento\Framework\Data\OptionSourceInterface;

/**
 * Class Profile
 * @package Vendor\Package\Model\Config\Source
 */
class Profile implements OptionSourceInterface
{
    /**
     * @return array
     */
    public function toOptionArray() : array
    {
        return [
            ['value' => '', 'label' => __('-- Select an Option --')],
            ['value' => 'grid', 'label' => __('Grid Only')],
            ['value' => 'list', 'label' => __('List Only')],
            ['value' => 'grid-list', 'label' => __('Grid (default) / List')],
            ['value' => 'list-grid', 'label' => __('List (default) / Grid')]
        ];
    }
}

Answer 3

Use these files:

system.xml

<field id="select" translate="label" type="select"
       sortOrder="30" showInDefault="1" showInWebsite="1" showInStore="1">
    <label>Select Option</label>
    <source_model>Vendor\Modulename\Model\Config\Source\Products</source_model>
</field>

Model file

Vendor\Modulename\Model\Config\Source;

use Magento\Framework\Option\ArrayInterface;

class Products implements ArrayInterface
{
    /*
     * Option getter
     * @return array
     */
    public function toOptionArray()
    {
        $arr = $this->toArray();
        $ret = [];
        foreach ($arr as $key => $value) {
            $ret[] = [
                'value' => $key,
                'label' => $value
            ];
        }
        return $ret;
    }

    /*
     * Get options in "key-value" format
     * @return array
     */
    public function toArray()
    {
        $choose = [
            '1' => 'A',
            '2' => 'B',
            '3' => 'C',
            '4' => 'D'
            
        ];
        return $choose;
    }
}

Answer 4

\Magento\Framework\Option\ArrayInterface is deprecated instead we can use \Magento\Framework\Data\OptionSourceInterface