如何在删除原始类别后将未分类的类别分配给 post

Question

我正在开发一个 laravel 博客项目，如果我删除一个类别，我希望该类别的所有 post 移动到 'Uncategorized' 类别。如果 post 属于已删除的类别和其他类别，则避免将 post 移至未分类，否则将 post 移至未分类。我正在为 Category-Post 模型使用多对多关系。请参阅下面的代码：

Post 我有迁移

Schema::create('posts', function (Blueprint $table) {
    $table->id();
    $table->foreignId('user_id')
    ->constrained()
    ->onDelete('cascade');

    $table->string('title')->unique();
    $table->string('featured_image')->nullable()->default('default_featured_image.jpg');
    $table->text('detail');
    $table->string('tags')->nullable();
    $table->timestamps();
});

类别迁移

public function up()
{
    Schema::create('categories', function (Blueprint $table) {
        $table->id();
        $table->string('title');
        $table->text('detail',300)->nullable();
        $table->string('image')->nullable();
        $table->timestamps();
    });
}

关系的枢轴迁移

public function up()
{
    Schema::create('category_post', function (Blueprint $table) {
        $table->id();
        $table->unsignedInteger('post_id');
        $table->unsignedInteger('category_id');
        $table->timestamps();
    });
}

Post 型号

 function categories(){
    return $this->belongsToMany(Category::class);
 }

类别模型

function posts(){
   return $this->belongsToMany(Post::class);
}

类别控制器

public function destroy(Request $request)
{
   $cat_id = $request->category_id;
   $category = Category::find($cat_id);

   $posts_to_update_category_id = $category->posts()->wherePivot('category_id','=',$cat_id)->get();
   foreach($posts_to_update_category_id as $post){
       $post = Post::find($post->id);
       $post->categories()->sync(1); //uncategorized id = 1
   }
   

   $category->delete();
   return redirect('admin/category')->with('success', ''.$category->title.' has been Deleted');
}

我的代码问题是它最终将所有 post 与已删除的类别 ID 更新为 1（未分类）。意思是如果我有 1 个 post 有两个不同的类别，比如 cat1 和 cat2，我删除了 cat1，我不希望这个 post 被移动到未分类，但我的代码确实移动了它并且也从中删除了 cat2使其只是未分类。如果可以的话请帮忙。谢谢

Answer 1

$category->posts()->wherePivot('category_id','=',$cat_id)->get(); 已经有 returns 个 post 实例，所以您以后 $post = Post::find($post->id); 不必再做

您可以验证它是否有多个类别，这意味着此 post 不应移至未分类，而只是删除类别对吗？

所以你可以这样做

public function destroy(Request $request)
{
   $cat_id = $request->category_id;
   $category = Category::find($cat_id);

   $posts = $category->posts()->with('categories')->wherePivot('category_id','=',$cat_id)->get();
   foreach($posts as $post){
       if (count($post->categories) > 1) {
           $post->categories()->detach($cat_id);
       } else {
           $post->categories()->sync(1); //uncategorized id = 1
       }
   }
   

   $category->delete();
   return redirect('admin/category')->with('success', ''.$category->title.' has been Deleted');
}

Answer 2

一个简单的解决方案是在删除类别时删除关系

关系的枢轴迁移

public function up()
{
    Schema::create('category_post', function (Blueprint $table) {
        $table->id();
        $table->unsignedInteger('post_id');
        $table->unsignedInteger('category_id');
        $table->timestamps();
        $table->foreignId('category_id')
            ->constrained(categories)
            ->onUpdate('cascade')
            ->onDelete('cascade');
        $table->foreignId('post_id')
            ->constrained(posts)
            ->onUpdate('cascade')
            ->onDelete('cascade');

    });
}

当您删除 post 或类别时，关系将被数据库中的级联自动删除

如何在删除原始类别后将未分类的类别分配给 post

How do I assign uncategorized category to a post after deleting it original category

php

laravel

many-to-many

blogs

updating