VirtualSelect
=============

* Published: 2019-07-25
* Author: Nickolas Burr

.. contents:: Table of Contents
    :local:

Related
-------

* :doc:`DataObjectFactory`
* :doc:`VirtualGroupedSelect`

Description
-----------

The use of dependency injection in Magento makes it especially easy to
work with data from ``di.xml``. However, it is still so commonplace to
see hardcoded data in backend ``source_model`` classes, which amounts to
a bunch of duplicated classes containing disparate data. Unifying the
data in ``di.xml`` makes it easier to maintain and update throughout the
lifetime of the module.

An elegant approach to creating select ``source_model`` classes with populated
data is to create a generic class that implements ``ArrayInterface``, and use
the power of the ``<virtualType>`` to set the options dynamically.

Usage
-----

.. code-block:: xml

    <?xml version="1.0"?>
    <!--
    /**
     * system.xml
     */
    -->
    <config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
            xsi:noNamespaceSchemaLocation="urn:magento:module:Magento_Config:etc/system_file.xsd">
        <system>
            <tab id="vendor" translate="label" sortOrder="100">
                <label>Vendor, Inc.</label>
            </tab>
            <section id="package" translate="label" sortOrder="100"
                     showInDefault="1" showInWebsite="1" showInStore="1">
                <class>separator-top</class>
                <label>Package</label>
                <tab>vendor</tab>
                <group id="general" translate="label" type="text" sortOrder="10"
                       showInDefault="1" showInWebsite="1" showInStore="1">
                    <label>General Settings</label>
                    <field id="default_status" translate="label" type="select" sortOrder="10"
                           showInDefault="1" showInWebsite="1" showInStore="1">
                        <label>Default Status</label>
                        <!-- The <virtualType> class -->
                        <source_model>Vendor\Package\Model\Source\Select\Status</source_model>
                    </field>
                </group>
            </section>
        </system>
    </config>

Source
------

.. code-block:: php

    <?php
    /**
     * Generic.php
     */
    declare(strict_types=1);

    namespace Vendor\Package\Model\Source\Select;

    use Magento\Framework\Option\ArrayInterface;

    class Generic implements ArrayInterface
    {
        /** @property array $options */
        protected $options = [];

        /**
         * @param array $data
         * @return void
         */
        public function __construct(array $data = [])
        {
            /* Inverts KV for array_walk. */
            $data = array_flip($data);

            array_walk(
                $data,
                [
                    $this,
                    'setOption'
                ]
            );
        }

        /**
         * @param int|string|null $value
         * @param int|string $key
         * @return void
         */
        protected function setOption($value, $key): void
        {
            $this->options[] = [
                'label' => __($key),
                'value' => $value,
            ];
        }

        /**
         * @return array
         */
        public function toOptionArray()
        {
            return $this->options;
        }
    }

.. code-block:: xml

    <?xml version="1.0"?>
    <!--
    /**
     * di.xml
     */
    -->
    <config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
            xsi:noNamespaceSchemaLocation="urn:magento:framework:ObjectManager/etc/config.xsd">
        <virtualType name="Vendor\Package\Model\Source\Select\Status"
                     type="Vendor\Package\Model\Source\Select\Generic">
            <arguments>
                <argument name="data" xsi:type="array">
                    <item name="pending" xsi:type="string">Pending</item>
                    <item name="closed" xsi:type="string">Closed</item>
                    <item name="open" xsi:type="string">Open</item>
                    <item name="on_hold" xsi:type="string">On Hold</item>
                </argument>
            </arguments>
        </virtualType>
    </config>