Modify a custom block field value with hook_form_alter and validate

Question

I'm trying to modify a custom block form with hook_form_alter .In its validate function I have a case where one of the field value needs to be unset. For modifying its value I tried with

$form_state->setValue('field_name', '') /

$form['field_name']['#default_value'] = '' /

$form['field_name']['#value'] = ''

But none of these approach seems to work. Below is my code -

function coolmodule_form_alter(&$form, FormStateInterface $form_state, $form_id) {
    //create or edit form
    if('block_content_coolblock_form' === $form_id || 'block_content_coolblock_edit_form' === $form_id) {
      $form['#validate'][] = 'coolblockvalidate';
    }
}

function coolblockvalidate(array &$form, FormStateInterface &$form_state) {
    //trying to unset the field value here, which is not working.
    $form_state->setValue('field_mycoolfield', '');

    //tried these approach too with no luck.
    //$form['field_mycoolfield']['#default_value'] = '';
    //$form['field_mycoolfield']['#default_value'] = '';

}

I'm very interested in knowing why the field value can't be changed. I tried the same with a custom form alter and it works.

Any ideas/ suggestions would save me. Thanks.

Answer 1

Got this working by adding a submit handler.

Below is the code -

function coolmodule_form_alter(&$form, FormStateInterface $form_state, $form_id) {
  //create or edit form
  if('block_content_coolblock_form' === $form_id || 'block_content_coolblock_edit_form' === $form_id) {
    //extra submit handler that will execute after default submit
    $form['actions']['submit']['#submit'][] = 'coolmodule_coolblocksubmit';
  }
}


function coolmodule_coolblocksubmit(array &$form, FormStateInterface &$form_state) {

  $entity = $form_state->getFormObject()->getEntity();
  // unset field.
  $entity->set('myfield', '');
  // Saving the entity.
  $entity->save();
}

Answer 2

You can unset the field using the Hook_preprocess_hook something like the following.

/**
 * Implements hook_preprocess_HOOK().
 */
function coolmodule_preprocess_block(&$variables) {
  if (
    isset($variables['elements']['content']['#block_content'])
   && $variables['elements']['content']['#block_content']->bundle() == 'your_custom_block_type'
  ) {
    if (isset($variables['content']['field_custom_field_test'])){
      //- set field to empty value
      $variables['content']['field_name'] = [];
      //- Or Unset the field totaly
      unset($variables['content']['field_name']);
    }
  }
}

Answer 3

You does not need to saved entity multiple time.

function coolmodule_form_alter(&$form, FormStateInterface $form_state, $form_id) {
  //create or edit form
  if('block_content_coolblock_form' === $form_id || 'block_content_coolblock_edit_form' === $form_id) {
    //extra submit handler that will execute after default submit
    array_unshift($form['actions']['submit']['#submit'] , 'coolmodule_coolblocksubmit');
  }
}


function coolmodule_coolblocksubmit(array &$form, FormStateInterface &$form_state) {

  $entity = $form_state->getFormObject()->getEntity();
  // unset field.
  $entity->set('myfield', '');
}