Magento 2.3 Show all data from table not working

Question

Block code(path: \magento\app\code\Sample\HelloWorld\Block\Index.php)

<?php 
namespace Sample\HelloWorld\Block;
use \Magento\Framework\View\Element\Template;
use Sample\HelloWorld\Model\PostFactory;

class Index extends Template {
    protected $_postFactory;
    public function __construct(
        Template\Context $context,
        PostFactory $postFactory
    ) {
        parent::__construct($context);
        $this->_postFactory = $postFactory;
    }
 
    public function getData()
    {
        $post = $this->_postFactory->create();
        $collection = $post->getCollection();
        return $collection;
    }
} 

Template file code (path: \magento\app\code\Sample\HelloWorld\view\frontend\templates\index.phtml)

<?php
/**
 * @var \Sample\HelloWorld\Block\Display $block
 */
?>
<h2>Hello <b>World</b></h2>

<table>
    <tr>
        <th><?= __('Post ID'); ?></th>
        <th><?= __('Name'); ?></th>
        <th><?= __('URL Key'); ?></th>
        <th><?= __('Post Contents'); ?></th>
        <th><?= __('Tags'); ?></th>
        <th><?= __('Status'); ?></th>
        <th><?= __('Updated At'); ?></th>
        <th colspan="2"><?= __('Action'); ?></th>
    </tr>
    <?php
        $collectionData = $block->getData();
        echo($collectionData);
        foreach($collectionData as $collection):
            print_r($collection);
        endforeach;
    ?>
    
    
</table>

Table structure:

Output is empty page. When I remove all code inside the Index class and just keep a hello world in the template, The hello world text is showing successfully.

Please help, I can't find the issue in this..

Answer 1

you are calling data from collection factory so,if you want to print data than you update your code by me code(below).

  $collectionData = $block->getData();
    foreach($collectionData as $collection):
        print_r($collection->getData());
    endforeach;

Answer 2

You can write function in block class file for fetching a collection and call that function in template file are as below example.

1] Block Class file

namespace vendorNanme\ModuleName\Block\Index;

use Magento\Framework\App\RequestInterface;
use vendorName\ModuleName\Model\Hello;

class Hello extends \Magento\Framework\View\Element\Template 
{
    protected $helloModelFactory;
    protected $request;

    public function __construct(
        \Magento\Catalog\Block\Product\Context $context,
        Hello $helloModelFactory,
        RequestInterface $request,
        array $data = []
    ) {
        parent::__construct($context, $data);
        $this->_helloModelFactory = $helloModelFactory;
        $this->_request = $request;
    }

    /**
     * Preparing global layout
     *
     * @return $this
     */
    protected function _prepareLayout() {
        parent::_prepareLayout();
        $this->pageConfig->getTitle()->set(__('Display Collection'));
        return $this;
    }

    public function getHello()
    {
        $collection = $this->_helloModelFactory->getCollection();
        return $collection;
    }
}

2] Template file (index.phtml)

<?php
//This line call the block class get hello function.
var_dump($block->getgetHello()->getData());

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