liwo/app/Models/Tag.php

<?php

namespace App\Models;

use App\Models\Model;

class Tag extends Model
{
    protected $fillable = ['business_id', 'label', 'color'];

    protected $reportable = [
        'label', 'color'
    ];

    public function getValueOf(?string $key)
    {
        $values = [
            'business_id' => $this->business_id,
            'project_id' => null,
            'sprint_id' => null,
            'workflow_id' => null,
            'status_id' => null,
            'system_id' => null,
            'user_id' => null,
            'task_id' => null,
            'subject_id' => $this->id,
        ];

        if ($key && isset($values, $key)) {
            return $values[$key];
        }

        return $values;
    }

    public function rules()
    {
        return [
            'label' => 'required|string|min:3|max:225',
            'color' => 'nullable|string|min:2|max:255',
        ];
    }

    public function business()
    {
        return $this->belongsTo(Business::class,'business_id','id',__FUNCTION__);
    }

    public function task()
    {
        return $this->belongsToMany(
            Task::class,'tag_task','tag_id','task_id',
            'id','id',__FUNCTION__
        );
    }
}