Question

多对多的关系有效。最初的工作迁移：

Schema::table('tag_topic', function (Blueprint $table) {
    $table->integer('topic_id')->unsigned()->index();
    $table->integer('tag_id')->unsigned()->index(); 
});

我希望删除引用项时删除数据透视表项。新迁移：

Schema::table('tag_topic', function (Blueprint $table) {
   $table->foreign('topic_id')->references('id')->on('topics') ->onDelete('cascade');
   $table->foreign('tag_id')->references('id')->on('tags')->onDelete('cascade');
});

数据透视表行项目未级联删除。

更新

我删除了表并重写了迁移，但仍然没有级联删除数据行：

    Schema::create('tag_topic', function (Blueprint $table) {
        $table->integer('topic_id')->unsigned();
        $table->integer('tag_id')->unsigned(); 
        $table->foreign('topic_id')->references('id')->on('topics')->onDelete('cascade');
        $table->foreign('tag_id')->references('id')->on('tags')->onDelete('cascade');
    });

此代码删除数据透视表行：

$tag = Tag::where('id', $tag->id)->get()->first();
$Tag->topics()->detach();

Answer 1

在应用外键约束之前尝试删除旧索引。

Schema::table('tag_topic', function (Blueprint $table) {
    $table->dropIndex(['topic_id']);
    $table->dropIndex(['tag_id']);

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

如何在数据透视表上创建要在级联上删除的迁移

1 个答案: