How can I use my own custom system settings in e-mail templates?

Question

I have this custom configuration in my system.xml:

<system>
    <section id="general">
        <group id="store_information">
            <field id="support_phone" translate="label" type="text" sortOrder="21" showInDefault="1" showInWebsite="1" showInStore="1">
                <label>Support Phone Number</label>
            </field>
        </group>
    </section>
</system>

And I want to use this in my e-mail templates. So naturally, I try something like:

{{config path="general/store_information/support_phone"}}

Now this doesn't render the variable. which makes sense. This was also a security issue in Magento 1 since it would allow you to peek into system configuration settings, like API keys and stuff. So I have to include these parameters. Now I've added to my di.xml the setting to the config exclude list and the source model used by the email module:

<type name="Magento\Config\Model\Config\Export\ExcludeList">
    <arguments>
        <argument name="configs" xsi:type="array">
            <item name="general/store_information/support_phone" xsi:type="string">1</item>
        </argument>
    </arguments>
</type>
<type name="Magento\Email\Model\Source\Variables">
    <plugin name="custom_plugin" type="Vendor\Module\Plugin\Magento\Email\Model\Source\Variables"/>
</type>

But still it doesn't work. So where is the setting so I can whitelist certain configuration settings to be used in e-mail templates?

Answer 1

I found the problem. In my source model I hooked into the toOptionArray()-method, but this had to be the getData()-method:

public function afterGetData(\Magento\Email\Model\Source\Variables $subject, $result)
{
    $result = array_merge($result, [
        [
            'value' => 'general/store_information/support_phone',
            'label' => __('Support Phone Number')
        ],
    ]);

    return $result;
}

Why? Because the filter used by the e-mail module uses the getData()-method to determine whether or not a config setting is allowed to be used. See \Magento\Email\Model\Template\Filter::isAvailableConfigVariable() for more details.