tissue/app/Ejaculation.php

<?php

namespace App;

use Illuminate\Database\Eloquent\Builder;
use Illuminate\Database\Eloquent\Model;
use Illuminate\Support\Facades\Auth;

class Ejaculation extends Model
{
    //

    protected $fillable = [
        'user_id', 'ejaculated_date',
        'note', 'geo_latitude', 'geo_longitude', 'link',
        'is_private'
    ];

    protected $dates = [
        'ejaculated_date'
    ];

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

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

    public function textTags()
    {
        return implode(' ', $this->tags->map(function ($v) {
            return $v->name;
        })->all());
    }

    public function likes()
    {
        return $this->hasMany(Like::class);
    }

    public function scopeWithLikes(Builder $query)
    {
        if (Auth::check()) {
            // (ejaculation_id, user_id) でユニークなわけですが、サブクエリ発行させるのとLeft JoinしてNULLかどうかで結果を見るのどっちがいいんでしょうね
            return $query->withCount([
                'likes',
                'likes as is_liked' => function ($query) {
                    $query->where('user_id', Auth::id());
                }
            ]);
        } else {
            return $query->withCount('likes')
                ->addSelect('0 as is_liked');
        }
    }
}