Getting old node field value in update hook

Question

Hi I'm using the node update hook in my custom .module file in my Drupal 9 site. I have a field called field_amount. And I was wondering if I can access the old value of that field within my update hook and the new value too?

function custom_module_node_update(\Drupal\node\NodeInterface $node) {
  //access the old value of field_amount and the new value
}

Answer 1

As the docs say:

Get the original entity object from $entity->original.

In your case that would be, for example:

function custom_module_node_update(\Drupal\node\NodeInterface $node) {
  $old_field_value = $node->original->field_foo->value;
}