silverstripe / silverstripe-asset-admin

        // Configure form to respond to validation errors with form schema

        // if requested via react.

        $form->setValidationResponseCallback(function (ValidationResult $errors) use ($form, $id, $versionId) {

            $schemaId = Controller::join_links($this->Link('schema/fileHistoryForm'), $id, $versionId);

            return $this->getSchemaResponse($schemaId, $form, $errors);

        });

        return $form;

    }

        $handler = AddToCampaignHandler::create($this, $record, 'addToCampaignForm');

        $form = $handler->Form($record);

        $form->setValidationResponseCallback(function (ValidationResult $errors) use ($form, $id) {

            $schemaId = Controller::join_links($this->Link('schema/addToCampaignForm'), $id);

            return $this->getSchemaResponse($schemaId, $form, $errors);

        });

        return $form;

    }