ldc-crm/app/Models/SingleOptin.php

<?php

namespace App\Models;

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

class SingleOptin extends Model
{
    use HasFactory;

    /**
     * The attributes that are mass assignable.
     *
     * @var string[]
     */
    protected $fillable = [
        'email'
    ];

    // * RELATIONS

    /**
     * Brand BelongsTo relation
     *
     * @return \Illuminate\Database\Eloquent\Relations\BelongsTo
     */
    public function brand()
    {
        return $this->belongsTo(Brand::class);
    }
}