How to get the value of a custom field in hook_node_presave?

Question

Using hook_form_alter I have added a custom field in my node creation form

function custom_assignments_form_alter(&$form, $form_state, $form_id) {
//print_r($form_id);exit;
if($form_id == 'node_assignment_form'){

    $lecture_options = array();
    $lecture_values = db_query("SELECT nid, title FROM `node_field_data` WHERE nid IN (SELECT entity_id FROM 
                        `node__field_module` WHERE bundle='lectures' AND field_module_target_id=:tid)", 
                        array(':tid' => $selectedWeek))->fetchAll();
    foreach($lecture_values AS $key => $value){
        $lecture_options[$value->nid] = $value->title;
    }
    //print("<pre>");print_r($lecture_options);exit;


    $form['field_after_lecture']['#access'] = FALSE;
    $form['field_after_lecture_tmp'] = array(
            '#title' => t('After Lecture'),
            '#required' => true,
            '#type' => 'select',
            '#options' => $lecture_options,
            //'#default_value' => print_r($form_state->getBuildInfo()['args']);exit;,
            '#weight' => 100,
            '#prefix' => '<div id="custom">',
            '#suffix' => '</div>'
    );
}}

How to get the value of field_after_lecture_tmp in hook_node_presave I printed the node fields using $node->toArray() function. But this field is not there. In Drupal 7 I was able to access it.

Answer 1

You can't get the value in the hook_node_presave() because this is not a node field, as you says is a custom field that you create altering the form.

In this case you need to add a custom submit handler to use the value, something like this inside the hook implementation:

function custom_assignments_form_alter(&$form, $form_state, $form_id) {
// ...
  if (isset($form['actions']['save_continue']['#submit'])) {
    array_unshift($form['actions']['save_continue']['#submit'], '_node_revision_delete_form_node_type_submit');
  }
// ...
}

And in the function you can access to the value and perform your actions

function _node_revision_delete_form_node_type_submit(array &$form, FormStateInterface $form_state) {
// Getting the form values.
  $field_after_lecture_tmp = $form_state->getValue('field_after_lecture_tmp');
}