Magento 2: What is Difference between Create & Get ObjectManager?

Question

I have below code. Which give same result either I use create or get

$orderId = 1;
$_objectManager = \Magento\Framework\App\ObjectManager::getInstance(); 
$this->orderPayment = $_objectManager->create('Magento\Sales\Api\Data\OrderPaymentInterface')->load($orderId);
$this->orderPayment = $_objectManager->get('Magento\Sales\Api\Data\OrderPaymentInterface')->load($orderId);
echo $this->orderPayment->getLastTransId();

So What is exactly difference between them? Which needs to be used & when?

Answer 1

• $_objectManager->create() creates new instance of the object, no-matter-what
• $_objectManager->get() first tries to find shared instance (already created), if it's not found - it just creates new shared instance

If you take a look at class Magento\Framework\ObjectManager\ObjectManager, you'll notice this block:

...
/**
 * Create new object instance
 *
 * @param string $type
 * @param array $arguments
 * @return mixed
 */
public function create($type, array $arguments = [])
{
 $type = ltrim($type, '\\');
 return $this->_factory->create($this->_config->getPreference($type), $arguments);
}
/**
 * Retrieve cached object instance
 *
 * @param string $type
 * @return mixed
 */
public function get($type)
{
 $type = ltrim($type, '\\');
 $type = $this->_config->getPreference($type);
 if (!isset($this->_sharedInstances[$type])) {
 $this->_sharedInstances[$type] = $this->_factory->create($type);
 }
 return $this->_sharedInstances[$type];
}
...

• Chen Hanhan: create () is like "new Class()" and get () is like 'Mage::getSingleton()', it will first check the same class instance is exists or not in memory. If the instance is created then it will return the same object from memory.

Answer 2

Do not use object manager (bad practice).

You have to pass \Magento\Sales\Api\OrderRepositoryInterface in construct of your class.

 protected $order;
 public function __construct(
 ..., 
 \Magento\Sales\Api\OrderRepositoryInterface $order
 ){
 ...
 $this->order = $order;
 }

Then you can do following:

$order = $this->order->get($orderId);
echo $order->getPayment()->getLastTransId();