ldc-crm/app/Models/SingleOptin.php

<?php

namespace App\Models;

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

class SingleOptin extends Model
{
    use HasFactory;

    /**
     * The primary key for the model.
     *
     * @var string
     */
    protected $primaryKey = 'hashcode';

    /**
     * The "type" of the primary key ID.
     *
     * @var string
     */
    protected $keyType = 'uuid';

    /**
     * Indicates if the IDs are auto-incrementing.
     *
     * @var boolean
     */
    public $incrementing = false;

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

    /**
     * Perform any actions required after the model boots.
     *
     * @return void
     */
    protected static function booted()
    {
        static::creating(function (self $model) {
            $model->hashcode = Str::uuid();
        });
    }

    // * RELATIONS

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