Php onDelete（'cascade'）不删除数据透视表上的数据

我有以下迁移：

 public function up()
    {
        Schema::create('topics_to_subscriptions', function (Blueprint $table) {
            $table->engine = 'InnoDB';
            $table->integer('topic_id')->unsigned();
            $table->integer('subscription_id')->unsigned();

            $table->foreign('topic_id')->references('id')->on('topics')->onDelete('cascade');
            $table->foreign('subscription_id')->references('id')->on('subscriptions')->onDelete('cascade');
        });
    }

我的理解是，当使用onDelete'cascade'时，如果我删除订阅，那么所有相关的TopicsToSubscriptions都将被删除

---

当我运行App\Subscription:：truncate时；已从“订阅”表中正确删除所有订阅，但未从主题\u到\u订阅中删除任何数据。我做错了什么？

您不应该能够截断外键引用的表。我怀疑你的外键从未正确使用过

public function up()
{
    Schema::create('youtube_topics_to_subscriptions', function (Blueprint $table) {
        $table->engine = 'InnoDB';
        $table->integer('topic_id')->unsigned();
        $table->integer('youtube_subscription_id')->unsigned();

        $table->foreign('topic_id')->references('id')->on('youtube_topics')->onDelete('cascade');
        $table->foreign('youtube_subscription_id')->references('id')->on('youtube_subscriptions')->onDelete('cascade');
    });
}