从taggables加载标签

Question

我想用这段代码显示过去4小时中最常用的4个标签：

$topTags = Taggable::whereDate('created_at', '>=', now()->subHours(4))
    ->groupBy('tag_id')
    ->orderByRaw('count(tag_id) DESC'))
    ->take(4)
    ->with('tags')
    ->get();

表

Schema::create('tags', function (Blueprint $table) {
            $table->increments('id');
            $table->string('name')->unique();
            $table->timestamps();
        });

 Schema::create('taggables', function (Blueprint $table) {
            $table->integer('tag_id');
            $table->integer('taggable_id');
            $table->string('taggable_type');
            $table->timestamps();
        });

标签表和标签之间需要什么关系？如何在视图中访问标签名称？如果我使用belongsTo关系：

class Taggable extends Model
{
    protected $fillable = ['tag_id', 'taggable_id', 'taggable_type'];

    public function tags()
    {
        return $this->belongsTo('App\Tag');
    }
}

标签数组为空：

 #relations: array:1 [▼
        "tags" => null
      ]

Answer 1

最初我建议taggable实体的tags（）关系名称应该只是tag（）。

那么Taggable实体应该有这样的“id”：

 Schema::create('taggables', function (Blueprint $table) {
            $table->increments('id');
            $table->integer('tag_id');
            $table->integer('taggable_id');
            $table->string('taggable_type');
            $table->timestamps();
    });

最后，Taggable实体应该具有这样的多态关系：

/**
 * @return \Illuminate\Database\Eloquent\Relations\MorphTo
 */
public function taggable()
{
    return $this->morphTo();
}

public function tag()
{
    return $this->belongsTo('App\Tag');
}

所以你可以像这样访问标签名称：

$topTags = Taggable::whereDate('created_at', '>=', now()->subHours(4))
    ->groupBy('tag_id')
    ->orderByRaw('count(tag_id) DESC'))
    ->take(4)
    ->with('tag')
    ->get();

foreach($topTags as $ttag){
    $ttag->tag->name;
}

不要忘记添加到与Taggable相关的其他实体：

/**
 * @return \Illuminate\Database\Eloquent\Relations\morphMany
 */
public function taggables()
{
    return $this->morphMany(Taggable::class, 'taggable');
}

像这样使用Taggable关系：

    $anyOtherModel->taggables()->create([
        'tag_id'     => $tag->id,
    ]);