Magento 2.0.x - Insert block in to the product page

Question

After about a week reading through the Magento 2 Docs - layout instructions, and some other stack exchange Q's and A's, I still having a hard time to figure out how to insert a custom block in to the specific location of the product page. What I have so far, in to the top of this page: /app/design/frontend/<Vendor>/<theme>/Magento_Catalog/templates/product/view/details.phtml

I have inserted this line of code:

echo $this->getLayout()->createBlock('Magento\Cms\Block\Block')->setBlockId('block_identifier')->toHtml();

In the product "Custom Lyout Update", i have inserted this XML

<referenceContainer name="block_identifier" >
    <block class="Magento\Framework\View\Element\Template" name="test_file" template="Magento_Theme::html/test.phtml"   />
</referenceContainer>

The only time I can see contents of my test.php file is when I change referenceContainer name to predefined blocks as "content" or "product.info".

Links that I found useful:
Magento2- Display Static Block in Phtml file & CMS page
Magento 2 - How to call a custom phtml file in another phtml file, xml layout, static block and cms page?
How to show the static blocks in Magento 2?
Magento 2 tutorial – How to use the new front-end templating system

My current temp fix
I insert test.phtml file to a specific product this way.

<referenceContainer name="main" >
    <container name="product.info.desc" htmlTag="div" htmlId="product-info-desc-id" htmlClass="product-info-class" >
        <block class="Magento\Framework\View\Element\Template" name="test_file" template="Magento_Theme::html/test.phtml"   />
    </container>
</referenceContainer>
<move element="product.info.desc" destination="content" after="product.info.media" />

Any help is greatly appreciated. Thank you.

Answer 1

(1) first create a new module with a custom eav for your product content (this is just the InstallData.php content):

<?php namespace <vendor>\<module_name>\Setup;

use Magento\Eav\Setup\EavSetup;
use Magento\Eav\Setup\EavSetupFactory;
use Magento\Framework\Setup\InstallDataInterface;
use Magento\Framework\Setup\ModuleContextInterface;
use Magento\Framework\Setup\ModuleDataSetupInterface;


/**
 * @codeCoverageIgnore
 */
class InstallData implements InstallDataInterface
{
    /**
     * EAV setup factory
     *
     * @var EavSetupFactory
     */
    private $eavSetupFactory;

    /**
     * Init
     *
     * @param EavSetupFactory $eavSetupFactory
     */
    public function __construct(EavSetupFactory $eavSetupFactory)
    {
        $this->eavSetupFactory = $eavSetupFactory;
        /* assign object to class global variable for use in other class methods */
    }

    /**
     * {@inheritdoc}
     * @SuppressWarnings(PHPMD.ExcessiveMethodLength)
     */
    public function install(ModuleDataSetupInterface $setup, ModuleContextInterface $context)
    {
        $setup->startSetup();
        /** @var EavSetup $eavSetup */
        $eavSetup = $this->eavSetupFactory->create(['setup' => $setup]);

        /**
         * Add attributes to the eav/attribute
         */
        $eavSetup->addAttribute(
            \Magento\Catalog\Model\Product::ENTITY,
            'my_attribute',
            [
                'type' => 'text',
                'backend' => '',
                'frontend' => '',
                'label' => 'my custom content',
                'input' => 'textarea',
                'class' => '',
                'source' => '',
                'global' => 1,
                'visible' => true,
                'required' => false,
                'user_defined' => true,
                'default' => 0,
                'searchable' => false,
                'filterable' => false,
                'comparable' => false,
                'visible_on_front' => false,
                'used_in_product_listing' => true,
                'wysiwyg_enabled' => true, // if you want a wysiwyg editor
                'unique' => false,
                'apply_to' => 'simple,configurable,virtual,bundle,downloadable,grouped',
                'group' => 'General'
            ]
        );
        $setup->endSetup();
    }
}

(2) in the module extend catalog_product_view.xml to insert your attribute: [I added mine as a new product tab]

<referenceBlock name="product.info.details">
    <block class="Magento\Catalog\Block\Product\View\Description" name="{SOME_NAME}" template="product/view/attribute.phtml" group="detailed_info">
        <arguments>
            <argument name="at_call" xsi:type="string">getMyAttribute</argument>
            <argument name="at_code" xsi:type="string">my_attribute</argument>
            <argument name="css_class" xsi:type="string">{some class if you like}</argument>
            <argument name="at_label" xsi:type="string">none</argument>
            <argument name="title" translate="true" xsi:type="string">My tab label</argument>
        </arguments>
    </block>
</referenceBlock>

(3) now you can go to your magento admin and insert custom content (even html) into the attribute content like for every other attribute

Answer 2

In app\code\Namespace\Modulename\view\frontend\layout\catalog_product_view.xml add like below code. You can use your required referenceContainer

<page xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:View/Layout/etc/page_configuration.xsd">
    <body>
        <referenceContainer name="alert.urls">
            <block class="Namespace\Modulename\Block\Catalog\Product\View\Module" name="textblock" as="textblock" after="-" template="catalog/product/view/textblock.phtml" />
        </referenceContainer>
    </body>
</page>