The old function retrieves an old input value flashed into the session:
<?php $value = old('value');

$value = old('value', 'default');
<?php         $data = array_merge($field->toArray(), [

            'error' => $errors->first($field->handle()) ?: null,

            'old' => old($field->handle()),

        ]);



        $data['field'] = view($field->fieldtype()->view(), $data);
<?php             'get_post' => Arr::sanitize($this->request->all()),

            'get' => Arr::sanitize($this->request->query->all()),

            'post' => $this->request->isMethod('post') ? Arr::sanitize($this->request->request->all()) : [],

            'old' => Arr::sanitize(old(null, [])),



            'site' => $this->site,

            'sites' => Facades\Site::all()->values(),