我的Drupal 8自定义模块在日志中创建错误

Question

我为Drupal 8.6和Drupal Commerce 2创建了一个自定义模块。它可以工作，但是当我查看drupal日志时，每次重新加载页面时都会收到PHP警告。我该如何纠正这些警告？commerce_marketplace_premium_merchant.module ：<?php/** * @file * Hook implementations of commerce_marketplace_premium_merchant module. */use Drupal\commerce_store\Entity\StoreType;use Drupal\commerce_product\Entity\ProductType;use Drupal\commerce_product\Entity\ProductVariationType;use Drupal\Core\Entity\Display\EntityViewDisplayInterface;use Drupal\Core\Url;use Drupal\Core\Form\FormStateInterface;use Drupal\commerce_product\Entity\ProductVariation;function commerce_marketplace_premium_merchant_form_commerce_order_item_add_to_cart_form_alter(&$form, FormStateInterface $form_state, $form_id) {  $current_store = \Drupal::service('commerce_store.current_store');  $owner = $current_store->getStore()->getOwner();  foreach ($form_state->getFormObject()->getEntity()->getPurchasedEntity()->getProduct()->getStores() as $store) {    $bundle = $store->bundle();    // Product type abonnement.    if ($bundle == 'online') {      if (isset($form["#attributes"]["class"]) && in_array("commerce-order-item-add-to-cart-form", $form["#attributes"]["class"])) {        $selectedVariationId = $form_state->get('selected_variation');        $selectedVariation = ProductVariation::load($selectedVariationId);        $form['actions']['submit']['#value'] = t('Subscribe');        if (!$owner->hasRole('marchand')) {          $form['actions']['submit']['#attributes']['class'] = array('button--add-to-cart', 'button button--primary', 'js-form-submit', 'form-submit', 'is-disabled', 'btn-warning', 'btn');          $form['actions']['submit']['#disabled'] = TRUE;        }      }    }

Answer 1

似乎这行是问题所在（并且有多个实例）：

$selectedVariation = ProductVariation::load($selectedVariationId);

如果$selectedVariationId是NULL，似乎导致错误。

也许用if (!empty($selectedVariationId))或类似的符号包围该块？