TYPO3 Render FLUID Template in Backend - typo3

Question

I have an extbase extension with this TCA:
$GLOBALS['TCA']['tt_content']['types']['list']['previewRenderer']['items_item']
= \Vendor\Name\Backend\Preview\PreviewRenderer::class;
and this tsconfig:
mod.web_layout.tt_content.preview.list.items_item = EXT:EXT/Resources/Private/Templates/Preview/Items.html
Everything works well if i write the complete Code in this template file. But if i change it and use Partials like this:
<f:render arguments="{_all}" partial="Preview/List"/>
I only get the following error:
Error while rendering FluidTemplate preview using /typo3conf/ext/EXT/Resources/Private/Templates/Preview/Items.html The Fluid template files "" could not be loaded.
How can i set the Partial and Layout path?
Ive tried ist with module via typoscript but it doesnt work.

Answer 1

It depends on what your PreviewRender is doing.
The StandardContentPreviewRenderer supports only a template-file, no layouts, no partials. It's using a FluidStandaloneView and only setting setTemplatePathAndFilename() without setting paths for other parts of the template (renderContentElementPreviewFromFluidTemplate()):
protected function ‪renderContentElementPreviewFromFluidTemplate(array $row): ?string
{
$tsConfig = BackendUtility::getPagesTSconfig($row['pid'])['mod.']['web_layout.']['tt_content.']['preview.'] ?? [];
$fluidTemplateFile = '';
if ($row['CType'] === 'list' && !empty($row['list_type'])
&& !empty($tsConfig['list.'][$row['list_type']])
) {
$fluidTemplateFile = $tsConfig['list.'][$row['list_type']];
} elseif (!empty($tsConfig[$row['CType']])) {
$fluidTemplateFile = $tsConfig[$row['CType']];
}
if ($fluidTemplateFile) {
$fluidTemplateFile = GeneralUtility::getFileAbsFileName($fluidTemplateFile);
if ($fluidTemplateFile) {
try {
$view = GeneralUtility::makeInstance(StandaloneView::class);
$view->setTemplatePathAndFilename($fluidTemplateFile);
$view->assignMultiple($row);
if (!empty($row['pi_flexform'])) {
$flexFormService = GeneralUtility::makeInstance(FlexFormService::class);
$view->assign('pi_flexform_transformed', $flexFormService->convertFlexFormContentToArray($row['pi_flexform']));
}
return $view->render();
} catch (\‪Exception $e) {
$this->logger->warning('The backend preview for content element {uid} can not be rendered using the Fluid template file "{file}"', [
'uid' => $row['uid'],
'file' => $fluidTemplateFile,
'exception' => $e,
]);
if (‪$GLOBALS['TYPO3_CONF_VARS']['BE']['debug'] && $this->‪getBackendUser()->isAdmin()) {
$view = GeneralUtility::makeInstance(StandaloneView::class);
$view->assign('error', [
'message' => str_replace(‪Environment::getProjectPath(), '', $e->getMessage()),
'title' => 'Error while rendering FluidTemplate preview using ' . str_replace(‪Environment::getProjectPath(), '', $fluidTemplateFile),
]);
$view->setTemplateSource('<f:be.infobox title="{error.title}" state="2">{error.message}</f:be.infobox>');
return $view->render();
}
}
}
}
return null;
}
If you want more advanced features in your preview, you have to extend/override this method.
Update:
StandaloneView extends TYPO3\CMS\Fluid\View\AbstractTemplateView, so you have also those setters:
setTemplate($templateName)
setTemplatePathAndFilename($templatePathAndFilename)
setTemplateRootPaths(array $templateRootPaths)
setPartialRootPaths(array $partialRootPaths)
setLayoutRootPaths(array $layoutRootPaths)
So setting paths for partials in your ‪renderContentElementPreviewFromFluidTemplate() should solve it:
$view->setPartialRootPaths([
\TYPO3\CMS\Core\Utility\GeneralUtility::getFileAbsFileName('EXT:extensionfolder/Resources/Private/Partials'),
]);