src/Formio/Service/SubmissionService.php
public function exists($form, Parameters $parameters = null): bool
    {
        $object = $this->execute('GET', 'http://www.mocky.io/v2/592c6f7311000029066df850');

        if ($object && property_exists($object, '_id') && $object->_id) {
            return true;
        }

        return false;
    }
public function exists($form, Parameters $parameters = null): bool
    {
        $object = $this->execute('GET', 'http://www.mocky.io/v2/592c6f7311000029066df850');

        if ($object && property_exists($object, '_id') && $object->_id) {
            return true;
        }

        return false;
    }
Check if a submission exists

@param string $form
@param \Ds\Component\Formio\Query\SubmissionParameters $parameters
@return boolean