coaching-schedule-form

  public function buildVariationForm(array &$form, FormStateInterface $form_state, $product_variation) {
    $delta_key = 'section-delta-'. $product_variation->id();
    $session_delta = $form_state->get($delta_key);
    if (empty($session_delta)) {
      $session_delta = 1;
      $form_state->set($delta_key, 1);
    }
    $element = [];
    $id = 'wrapper-' . $product_variation->id();
    $element['section_container'] = [
      '#type' => 'container',
      '#prefix' => '<div id="' . $id . '">',
      '#suffix' => '</div>',
    ];
    $element['section_container']['section_title'] = [
      '#type' => 'html_tag',
      '#tag' => 'h3',
      '#value' => $product_variation->getTitle()
    ];
    for ($delta = 0; $delta < $session_delta; $delta ++) {
      $element['section_container'][$delta]['date_and_time'] = [
        '#type' => 'details',
        '#title' => $this->t('Date and Time'),
        '#open' => TRUE
      ];
      $element['section_container'][$delta]['date_and_time']['start_date'] = [
        '#type' => 'datetime',
        '#title' => 'Start Date and Time',
        '#default_value' => time(),
        '#required' => TRUE
      ];
      $element['section_container'][$delta]['date_and_time']['end_time'] = [
        '#type' => 'datetime',
        '#title' => 'End Time',
        '#default_value' => time(),
        '#date_date_element' => 'none',
        '#date_time_element' => 'time',
        '#required' => TRUE
      ];
    }
    $element['section_container']['add_session'] = [
      '#type' => 'submit',
      '#limit_validation_errors' => [],
      '#submit' => ['::incrementDelta'],
      '#value' => $this->t('Add Session'),
      '#ajax' => [
        'callback' => '::addSession',
        'wrapper' => $id
      ],
      '#product_variation' => $product_variation->id()
    ];
    $form[$product_variation->id()] = $element;
  }