Why the view block under the search field was not rendered?

Question

I created a block based on the view with machine name search_entity_product_block:

Then I created a custom form with method someMethod which should render a block of the view below the search field:

class SearchFieldForm extends FormBase {

  public function getFormId() {
    return 'entity_product_admin_search_field';
  }

  public function someMethod($args) {

    $view = [
      '#type' => 'view',
      '#name' => 'search_entity_product',
      '#display_id' => 'search_entity_product_block',
      '#arguments' => $args,
      '#embed' => TRUE,
    ];

    return $view;
  }

  public function buildForm(array $form, FormStateInterface $form_state) {

    $form['search_field'] = [
      '#type' => 'textfield',
      '#title' => $this->t('Search Product'),
    ];
    $form['submit'] = [
      '#type' => 'submit',
      '#value' => $this->t('Save'),
    ];

    return $form;
  }

  public function submitForm(array &$form, FormStateInterface $form_state) {
    $args = $form_state->getValue('search_field');
    $this->someMethod($args);
  }

}

But the block didn't render.

Answer 1

The submit function needs only to request a form rebuild and then the form build method can place the View block under the search field:

class SearchFieldForm extends FormBase {

  public function getFormId() {
    return 'entity_product_admin_search_field';
  }

  public function someMethod($args) {

    $view = [
      '#type' => 'view',
      '#name' => 'search_entity_product',
      '#display_id' => 'search_entity_product_block',
      '#arguments' => $args,
      '#embed' => TRUE,
    ];

    return $view;
  }

  public function buildForm(array $form, FormStateInterface $form_state) {

    $form['search_field'] = [
      '#type' => 'textfield',
      '#title' => $this->t('Search Product'),
    ];

    $args = $form_state->getValue('search_field');
    if ($args) {
      $form['result'] = $this->someMethod($args);
    }

    $form['submit'] = [
      '#type' => 'submit',
      '#value' => $this->t('Save'),
    ];

    return $form;
  }

  public function submitForm(array &$form, FormStateInterface $form_state) {
    $form_state->setRebuild();
  }

}