php_laravel_laracasts/app/Post.php

<?php

namespace App;

use Carbon\Carbon;

class Post extends Model
{

    /**
     * These fields are OK for mass assignement.
     *
     * @var array
     */
    protected $fillable = ['body', 'title', 'user_id'];

    /**
     * @param string $body
     */
    public function addComment(string $body)
    {
//      Comment::create([
//          'body' => $body,
//          'post_id' => $this->id,
//      ]);

        $this->comments()->create(compact('body'));
    }

    public function comments()
    {
        return $this->hasMany(Comment::class);
    }

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

    /**
     * Enables a "filter()" method on Post queries.
     */
    public function scopeFilter($query, array $filters = [])
    {
        if ($month = $filters['month'] ?? NULL)
        {
            /* When parsing just a month name, Carbon returns a date built
            from the current date at midnight, with the month replaced by the
            specified month name */
            $query->whereMonth('created_at', Carbon::parse($month)->month);
        }

        if ($year = (int) $filters['year'] ?? NULL)
        {
            /* When parsing just a month name, Carbon returns a date built
            from the current date at midnight, with the month replaced by the
            specified month name */
            $query->whereYear('created_at', $year);
        }

        return $query;
    }
}