Laravalio 官方开源论坛，Trait 的使用让我开了眼界，学习中

不多说废话，看下面的代码是HasSlug这个trait，其中这个地方 return static::where('slug', $slug)->firstOrFail();
这节这么来弄，是不是这个trait必须要在model用才可以啊，否则where怎么找得到？

只能说，这个trait太神奇了！！！！

<?php

namespace App\Helpers;

trait HasSlug
{
    public function slug(): string
    {
        return $this->slug;
    }

    public function setSlugAttribute(string $slug)
    {
        $this->attributes['slug'] = $this->generateUniqueSlug($slug);
    }

    public static function findBySlug(string $slug): self
    {
        return static::where('slug', $slug)->firstOrFail();
    }

    private function generateUniqueSlug(string $value): string
    {
        $slug = $originalSlug = str_slug($value);
        $counter = 0;

        while ($this->slugExists($slug, $this->exists ? $this->id() : null)) {
            $counter++;
            $slug = $originalSlug.'-'.$counter;
        }

        return $slug;
    }

    private function slugExists(string $slug, int $ignoreId = null): bool
    {
        $query = $this->where('slug', $slug);

        if ($ignoreId) {
            $query->where('id', '!=', $ignoreId);
        }

        return $query->count();
    }
}