Question

我正在关注有关Laracasts的多对多关系Laravel教程-https://laracasts.com/series/laravel-5-fundamentals/episodes/21

我面临的挑战是，我创建了数据透视表article_tag) to keep track of the many to many relations. Articles can have many tags, and tags can have many articles. So I can run sync etc to associate tagX tagY tagZ to article1`。但是，我还希望能够有选择地将关联标签之一设置为“ isGreenTag”。我可以在跟踪多对多关系的数据透视表中执行此操作吗？我可以添加一列“ is_green_tag”吗？

这是我的Article班级关系：

class Article extends Model {
   public function tags() {
      return $this->belongsToMany('App\Tag')->withTimestamps();
   }
}

这是我的Tag班级关系：

class Tag extends Model {
   public function articles() {
      return $this->belongsToMany('App\Articles');
   }
}

这是我对数据透视表的迁移：

public function up() {
    Schema.create('article_tag', function(Blueprint $table) {
        $table->integer('article_id')->unsigned()->index();
        $table->foreign('article_id')->references('id')->on('articles')->onDelete('cascade');

        $table->integer('tag_id')->unsigned()->index();
        $table->foreign('tag_id')->references('id')->on('tags')->onDelete('cascade');

        $table->timestamps();
    });
}

我可以添加到数据透视表迁移$table->boolean('is_green_tag')->nullable()吗？

Answer 1

是的，可以给它一个默认的0而不是使其可以为空：

$table->boolean('is_green_tag')->default(0);

然后您可以修改Article类上的关系：

public function tags() {
    return $this->belongsToMany('App\Tag')->withPivot(['is_green_tag'])->withTimestamps();
}

一旦有了Article对象，就可以访问该属性：

foreach ($article->tags as $tag) {
    if ($tag->pivot->is_green_tag) {
        // some logic here
    }
}

要为is_green_tag保存$tagId：

$article->tags()->attach($tagId, ['is_green_tag' => 1]);

Laravel文档：
https://laravel.com/docs/5.7/eloquent-relationships#many-to-many https://laravel.com/docs/5.7/eloquent-relationships#updating-many-to-many-relationships

使用数据透视表获取其他属性？

1 个答案: