eZ\Publish\Core\MVC\Symfony\Templating\Twig\Extension\FieldRenderingExtension::getFieldTypeIdentifier PHP Method

    private function getFieldTypeIdentifier(Content $content, Field $field)
    {
        $contentInfo = $content->getVersionInfo()->getContentInfo();
        $key = $contentInfo->contentTypeId . '  ' . $field->fieldDefIdentifier;
        if (!isset($this->fieldTypeIdentifiers[$key])) {
            $contentType = $this->contentTypeService->loadContentType($contentInfo->contentTypeId);
            $this->fieldTypeIdentifiers[$key] = $contentType->getFieldDefinition($field->fieldDefIdentifier)->fieldTypeIdentifier;
        }
        return $this->fieldTypeIdentifiers[$key];
    }