Constants in config.xml

Question

Is it possible to use PHP class constants as values in the config.xml file?

For example, if we have this config.xml file:

<?xml version="1.0"?>
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:module:Magento_Store:etc/config.xsd">
    <default>
        <custommodule>
            <settings>
                <is_active>1</is_active>
                <mode>MODE</mode>
                <send_notification_email>0</send_notification_email>
            </settings>
        </custommodule>
    </default>
</config>

I would like to use a PHP class constant to output the value for the "mode". Is there a way to achieve this?

Answer 1

You can use a backend_model in your config.xml node:

<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:module:Magento_Store:etc/config.xsd">
    <default>
        <your>
            <path>
                <field backend_model="Vendor\Module\Model\Config"/>
            </path>
        </your>
    </default>
</config>

Then, in \Vendor\Module\Model\Config:

class \Vendor\Module\Model\Config implements \Magento\Framework\App\Config\Data\ProcessorInterface
{
    const MY_CONST = 'My constant value';

    public function processValue($value)
    {
        return self::MY_CONST;
    }
}

From there, any additional complex logic can be added.

Answer 2

This should be possible using PHPs constant method.

Something like this:

$configValue = $this->scopeConfig->getValue(
   'custommodule/settings/mode',
   ScopeInterface::SCOPE_STORE
);

$constantValue = constant($configValue);