Magento order-data showing null in sales_order_place_before observer

Question

I have created a new observer to check the order data passing with "sales_order_place_before" event in observer.My observer is working but when I am trying to fetch the observer event data am getting null values.Please help me resolve this issue.Thanks in advance. My observer file

    namespace Custom\Order\Observer;

    use Magento\Framework\Event\ObserverInterface;

    class OrderPlacebefore implements ObserverInterface
    {
     protected $_objectManager;

      public function __construct(
        \Magento\Framework\ObjectManagerInterface $objectManager
      ) {
          $this->_objectManager = $objectManager;
      }

      public function execute(\Magento\Framework\Event\Observer $observer)
      {     
        $event = $observer->getEvent();
        $orderObserverData = $observer->getEvent()->getData();
        $writer = new \Zend\Log\Writer\Stream(BP . '/var/log/test.log');
        $logger = new \Zend\Log\Logger();
        $logger->addWriter($writer);
        $logger->info('mY obsever');
       $logger->info('data' . json_encode($orderObserverData));
      }
    }

Answer 1

To get the data from the event you need to make some small change in your code like below

public function execute(\Magento\Framework\Event\Observer $observer)
  {
        $event = $observer->getEvent();
        $orderObserverData = $$observer->getEvent()->getOrder()->getData();
        $writer = new \Zend\Log\Writer\Stream(BP . '/var/log/test.log');
        $logger = new \Zend\Log\Logger();
        $logger->addWriter($writer);
        $logger->info('orderData' . json_encode($orderObserverData));

  }

Answer 2

Try following code:

1. app/code/[VendorName]/[ModuleName]/etc/events.xml

<?xml version="1.0"?>
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:Event/etc/events.xsd">
    <event name="sales_order_place_before">
        <observer name="[VendorName]_[ModuleName]_sales_order_place_before" instance="[VendorName]\[ModuleName]\Observer\OrderPlacebefore"/>
    </event>
</config>

2. app/code/[VendorName]/[ModuleName]/Observer/OrderPlacebefore.php

<?php
namespace [VendorName]\[ModuleName]\Observer;

use Magento\Framework\Event\ObserverInterface;

class OrderPlacebefore implements ObserverInterface
{
    protected $_objectManager;

    public function __construct(
        \Magento\Framework\ObjectManagerInterface $objectManager
    ) {
        $this->_objectManager = $objectManager;
    }

    public function execute(\Magento\Framework\Event\Observer $observer)
    {
        $orderObserverData = $observer->getOrder()->getData();

        $writer = new \Zend\Log\Writer\Stream(BP . '/var/log/test.log');
        $logger = new \Zend\Log\Logger();
        $logger->addWriter($writer);
        $logger->info('OrderPlacebefore:');
        $logger->info('data' . json_encode($orderObserverData));
    }
}