liwo/app/Models/Fingerprint.php

<?php

namespace App\Models;

use App\Models\Model;

class Fingerprint extends Model
{
    protected $fillable = ['user_id', 'agent', 'ip', 'os', 'latitude', 'longitude', 'token', 'fcm_token'];

    protected $table = 'fingerprints';

    public function user()
    {
        return $this->belongsTo(User::class, 'user_id', 'id', __FUNCTION__);
    }

    public function rules()
    {
        return [
            'user_id' => 'required|integer|exists:users,id',
            'agent' => 'required|string',
            'ip' => 'required|ip',
            'os' => 'required|string',
            'latitude' => 'required',
            'longitude' => 'required',
            'token' => 'required|string|min:60',
            'fcm_token' => 'nullable',
        ];
    }
}