Magento2 Plugin with Proxy

Question

In my test extension I try create plugin for Magento\Directory\Helper\Data::isRegionRequired method. My frontend/di.xml contain:

<type name="Magento\Directory\Helper\Data">
    <plugin name="Sample_Test::isRegionRequired" type="Sample\Test\Plugin\Country\DirectoryHelperAfter" sortOrder="1" disabled="false"/>
</type>

And class Sample\Test\Plugin\Country\DirectoryHelperAfter contain

public function afterIsRegionRequired($subject, $result)
{
    exit('test');
    $myResult = true;
    return $myResult;
}

On the front I get next error on generating my plugin (before call plugin method):

Source class "\DirectoryHelperData" for "DirectoryHelperDataProxy" generation does not exist.

In /app/code/Magento/Directory/etc/di.xml I found:

<virtualType name="DirectoryHelperDataProxy" type="Magento\Directory\Helper\Data\Proxy">
    <arguments>
        <argument name="instanceName" xsi:type="string">Magento\Directory\Helper\Data</argument>
    </arguments>
</virtualType>
<type name="Magento\Directory\Model\ResourceModel\Country\Collection" shared="false">
    <arguments>
        <argument name="helperData" xsi:type="object">DirectoryHelperDataProxy</argument>
    </arguments>
</type>

My question is "How I can use plugin for class if it used in proxy"?

Answer 1

From https://devdocs.magento.com/guides/v2.0/extension-dev-guide/plugins.html:

Limitations

Plugins cannot be used with any of the following:

• Final methods
• Final classes
• Any class that contains at least one final public method
• Non-public methods
• Class methods (such as static methods)
• __construct
• Virtual types

As this is Virtual type, you can't use plugin for Magento\Directory\Helper\Data I have encountered the same problem, the best solution I have found is to use preference.

<preference for="Magento\Directory\Helper\Data" type="Sample\Test\Helper\Data" />

It works as override of methods.

Answer 2

How I can use plugin for class if it used in proxy ?

The plugin (before, after and around ) will work same even the class is used by proxy.

Let us have a quick working example.. taken

di.xml

<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="../../../../../lib/internal/Magento/Framework/ObjectManager/etc/config.xsd">
    <type name="Pulsestorm\TutorialProxy1\Model\Example">
        <arguments>
            <argument name="slow" xsi:type="object">Pulsestorm\TutorialProxy1\Model\SlowLoading\Proxy</argument>
        </arguments>
    </type>
    <type name="Pulsestorm\TutorialProxy1\Model\SlowLoading">
        <plugin name="pulsestorm_tutorial_plugin_model_example_plugin"
                type="Pulsestorm\TutorialProxy1\Model\Example\SlowLoading\Plugin"
                sortOrder="10"
                disabled="false"/>
    </type> 
</config>

The above di.xml, as we know we are using proxy class for Pulsestorm\TutorialProxy1\Model\SlowLoading and same class is used by plugin. so inside my Pulsestorm\TutorialProxy1\Model\Example\SlowLoading\Plugin

namespace Pulsestorm\TutorialProxy1\Model\Example\SlowLoading;

class Plugin
{
    public function afterHello()
    {
        echo "ABCD EFGH";

    }  


}

This afterHello method is working fine even the class is using proxy ....:)