how to get the original entity on hook_entity_presave?

Question

i actually need it for the content_moderation_state entity

 function hook_entity_presave(Drupal\Core\Entity\EntityInterface $entity) {
if ($entity->getEntityTypeId() !== 'content_moderation_state' ) {
    return;
}    
$moderation_state = $entity->get('moderation_state')->getString();

 //code to get the original entity moderation state

Answer 1

Use $entity->original to get the original entity:

function hook_entity_presave(Drupal\Core\Entity\EntityInterface $entity) {

  if ($entity->getEntityTypeId() !== 'content_moderation_state' ) {
    return;
  }    

  $moderation_state = $entity->get('moderation_state')->getString();

  //code to get the original entity moderation state
  $moderation_state_original = $entity->original->get('moderation_state')->getString();

Answer 2

If for some reason the original property isn't available(in my case in the save() method of a custom content entity) you can get it as

$entityOriginal = \Drupal::entityTypeManager()
  ->getStorage('my_entity')
  ->loadUnchanged($entity->id());