symfony 4:集合类型的“允许删除”选项的逻辑在哪里?

您可以在中找到函数 MergeCollectionListener.php 从第91行开始:

// Remove deleted items before adding to free keys that are to be
// replaced
if ($this->allowDelete) {
        foreach ($itemsToDelete as $key) {
            unset($dataToMergeInto[$key]);
        }
    }

$dataToMergeInto 设置为 $dataToMergeInto = $event->getForm()->getNormData(); 它指的是一个函数,其中 FormInterface.php :

/**
 * Returns the normalized data of the field.
 *
 * @return mixed When the field is not submitted, the default data is returned.
 *               When the field is submitted, the normalized submitted data is
 *               returned if the field is valid, null otherwise.
 */
public function getNormData();