Magento2 – Add Message on Product Page

full-page-cacheglobal-messagesmagento2

I want to add a warning message on the product page but it's not working if full page cache is enabled.
I'm using the following event

<event name="controller_action_predispatch_catalog_product_view">
        <observer name="product_view_custom_action" instance="My\Module\Observer\Custom"/>
</event>

And in observer execute I have the following

$this->messageManager->addWarningMessage(__('My warning message'));

Is there a method that I could do this to show the warning message every time. Even after the page is cached?

Best Answer

you can use magento event http_response_send_before.

Related Solutions

Magento – Disable Full Page Cache of Widget+Banner Blocks

First of all you need to keep in mind that when you are in FPC cached page, the block is not getting created via layout. So first time when FPC page gets popuplated getChildHtml() returns you a correct block, but second time, it will not instantiate it, since Layout XML is not applied at all on cached response.

Any block you are referring to within FPC scope, should be created manually without using layout xml, so you can re-use it even, when layout is not available.

As far as I know, banners already FPC compatible, you should take a look into: Enterprise_PageCache_Model_Container_Banner

Magento2 – How to Change Response Before Full Page Cache

So, finally I have a real solution. So I was able to track down Magento2 full page cache and turned out that it does the caching as a plugin: Magento\PageCache\Model\App\FrontController\BuiltinPlugin in the aroundDispatch.

$this->kernel->process($result);

Does the work of storing the serialized $response object.

So the solution was to create a plugin for the after event:

Roland/HelloWorld/etc/di.xml

<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
        xsi:noNamespaceSchemaLocation="urn:magento:framework:ObjectManager/etc/config.xsd">
    <type name="Magento\Framework\Controller\ResultInterface">
        <plugin name="change-result-before-cache" type="Roland\HelloWorld\Model\Plugins\ChangeResult"/>
    </type>
</config>

Roland/HelloWorld/Model/Plugins/ChangeResult.php

<?php

namespace Roland\HelloWorld\Model\Plugins;

use Magento\Framework\App\Response\Http as ResponseHttp;


class ChangeResult {

    public function afterRenderResult(ResponseHttp $response) {
        $response->setBody(preg_replace('/<\/head>/', '<script>alert("' . time() . '");</script>' . '</head>', $response->getBody(), 1));
    }

}

The result

When page cache enabled, you should always see the same timestamp for every refresh.

Best Answer

Related Solutions

Magento – Disable Full Page Cache of Widget+Banner Blocks

Magento2 – How to Change Response Before Full Page Cache

The result

Related docs

Related Topic