I am parsing pdf's in a field for a custom content type in a cron job. I have a boolean on each node that determines whether their pdf has already been parsed. I grab the ones I need like so:

$query = \Drupal::entityQuery('node')
    ->condition('type', 'issue')
if($range > 0){

$issue_nids = $query->execute();
$issue_nodes = \Drupal::entityTypeManager()->getStorage('node')->loadMultiple($issue_nids);

foreach ($issue_nodes as $issue_node){
    //do my pdf parsing magic on field_pdf
    $node->field_indexed->value = true;

This works fine but if the user replaces field_pdf and uploads a new one I want to make field_indexed false again so I know to reindex it. The problem is I don't really have a way of knowing whether the field changed.

I considered using a presave hook but I didn't see a way to compare the form state to what was currently on the node.

Is there a way I can detect when a field has changed when a node has saved?

  • 2
    Use a presave hook, you have access to $entity->original, which contains the original’s field values. Use those for comparison
    – Clive
    Aug 3, 2018 at 15:36

1 Answer 1


Clive is correct. $node->original does give access to the original node values. I was able to accomplish what I needed like so

function my_module_node_presave($node) {
    $type = $node->getType();
    if($type == 'issue'){
            if(isset($node->field_pdf->entity) && !isset($node->original->field_pdf->entity) || empty($node->original->field_pdf->entity) || $node->field_pdf->entity->id() != $node->original->field_pdf->entity->id()){
                $node->field_indexed->value = false;
            } else {
                $node->field_indexed->value = true;
  • 2
    You might be able to simplify that to $node->set('field_indexed', !$node->get('field_pdf')->equals($node->original->get('field_pdf'))). You could also do a hasField('field_pdf'), most of the time I prefer checking for the existence of a field over a node type check because that allows you to e.g. add another node type that should have the same functionality later on
    – Berdir
    Aug 3, 2018 at 21:58
  • 2
    Actually, you might want to keep the if () but remove the else.. only the process that actually indexes those nodes should set it to true again. Imagine a user uploads a new PDF, then saves, which sets it to false and then immediately edits and saves again to fix a typo, your current code would set it to indexed thn
    – Berdir
    Aug 3, 2018 at 21:59

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