How to change a collection field value with presave I'm using field_collection module, and $question is a collection field. 

$question-&gt;value = 'test';
$node_poll-&gt;save();


The above code works for update this collection field value. Problem is this cannot be used for presave.

$question-&gt;value = 'test';
//$node_poll-&gt;save(); // I removed this since it does not need for a presave.


When I use above code for a presave hook. The value did not change. 

How to set a value for this collection field with presave with D8?
This code worked for me need to add  in presave hook  
//field collection field  
  $item = $entity->get('field_items')->value;

$fc = FieldCollectionItem::load($item);

foreach ($fc as $fckey => $field) { 
    if ($fckey == 'field_name') {
      $value = $field->getValue(); 
      $value = strip_tags($value[0]['value']);
      $summary_value = $entity->get('field_fc_child')->value;
      $entity->set('field_fc_child', $value);
    }
  }