laravel-sensors/app/Models/Sensor.php

<?php

namespace App\Models;

use Illuminate\Database\Eloquent\Factories\HasFactory;
use Illuminate\Database\Eloquent\Model;

class Sensor extends Model
{
    use HasFactory;
    
    /**
     * The attributes that are mass assignable.
     *
     * @var array
     */
    protected $fillable = [
        'status',
        'longitude',
        'latitude',
    ];

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