laravel-learn-bbs/app/Models/Topic.php

<?php

namespace App\Models;

/**
 * Class Topic
 * @property int id
 * @property string title
 * @property int category_id
 * @property int user_id
 * @property int reply_count
 * @property int view_count
 * @property int last_reply_user_id
 * @property string body
 * @property string slug
 * @property string excerpt
 * @property string created_at
 * @property string updated_at
 * @package App\Models
 */
class Topic extends Model
{
    protected $fillable = ['title', 'category_id', 'body', 'excerpt', 'slug'];


    public function link($params = [])
    {
        return route('topics.show', array_merge([$this->id, $this->slug], $params));
    }

    public function scopeWithOrder($query, $order)
    {
        // 不同的排序，使用不同的数据读取逻辑
        switch ($order) {
            case 'recent':
                $query = $this->recent();
                break;

            default:
                $query = $this->recentReplied();
                break;
        }
        // 预加载防止 N+1 问题
        return $query->with('user', 'category');
    }

    public function scopeRecentReplied($query)
    {
        // 当话题有新回复时，我们将编写逻辑来更新话题模型的 reply_count 属性，
        // 此时会自动触发框架对数据模型 updated_at 时间戳的更新
        return $query->orderBy('updated_at', 'desc');
    }

    public function scopeRecent($query)
    {
        // 按照创建时间排序
        return $query->orderBy('created_at', 'desc');
    }


    public function replies()
    {
        return $this->hasMany(Reply::class);
    }

    public function user()
    {
        return $this->belongsTo(User::class);
    }

    public function category()
    {
        return $this->belongsTo(Category::class);
    }
}