clqms-be/app/Models/ContactDetailModel.php

<?php

namespace App\Models;

use CodeIgniter\Model;

class ContactDetailModel extends Model {
  protected $table      = 'contactdetail';
  protected $primaryKey = 'ContactDetID';
  protected $allowedFields = ['ContactID', 'SiteID', 'ContactCode', 'ContactEmail', 'OccupationID', 'JobTitle', 'Department', 'ContactStartDate', 'ContactEndDate']; 

  public function syncDetails(int $contactId, array $details) {
    $kept = [];

    foreach ($details as $detail) {
      $detail['ContactID'] = $contactId;

      $existing = $this->where('SiteID', $detail['SiteID'])
        ->where('ContactID', $contactId)
        ->first();

        if ($existing) {
          $this->update($existing[$this->primaryKey], $detail);
          $kept[] = $existing[$this->primaryKey];
        } else {
          $newId = $this->insert($detail);
          $kept[] = $newId;
        }
    }

    if (!empty($kept)) {
      $this->where('ContactID', $contactId)
        ->whereNotIn($this->primaryKey, $kept)
        ->delete();
    } else { $this->where('ContactID', $contactId)->delete(); }
  }
}