How to limit showPrevNext in news to categories? - typo3

Question

In the TYPO3 CMS 9.5.18 LTS with tx_news 8.3.0 we use the following extension Typoscript:
plugin.tx_news.settings{
# what is allowed to overwrite with TS
overrideFlexformSettingsIfEmpty := addToList(categories)
overrideFlexformSettingsIfEmpty := addToList(categoryConjunction)
# ids of categories
categories = 3
# category conjunction mode
categoryConjunction = or
}
I wonder why I have to add categories to overrideFlexformSettingsIfEmpty to get the result below. Never the less this post is more about how to achieve that the prev/next links (settings.detail.showPrevNext) does respect the category definition at all.
Our customer has 3 categories for news. If I go to a single page that does has a one category limitation (for the detail and the list page) I still e.g. can go "forward" to newer news in a total different category. However the list page only shows the news of that one selected category.
<f:if condition="{paginated.prev}">
<n:link newsItem="{paginated.prev}" settings="{settings}" class="ts-prev">
{paginated.prev.title}
</n:link>
</f:if>
Wasn't that never the case? Do I have to add some Typoscript or make a change in Fluid? The original code uses this settings variable as argument which contains the category limitation.

Answer 1

Okay I've had a look into the GeorgRinger\News\ViewHelpers\SimplePrevNextViewHelper and there aren't any limitation for the current chosen categories.
So here is what I did:
register a new optional argument categories to the viewhelper
add categories="{settings.categories}" to the simplePrevNext tag in the Detail.html
add an 'extra where' for the main query in the getNeighbours function
add the content for the additional where ( I did that first in the getNeighbours function )
Extra where:
if( is_array($newsOfCategory) && count($newsOfCategory) > 0 ){
$extraWhere[] = $queryBuilder->expr()->in('uid', $queryBuilder->createNamedParameter($newsOfCategory, Connection::PARAM_INT_ARRAY));
}
Content for the additional where:
if( is_string($categories) && preg_match('/^[0-9]+(,[0-9]+)*$/',$categories) ){
$categories = explode(',', $categories);
$tmpCon = GeneralUtility::makeInstance(ConnectionPool::class)->getConnectionForTable('sys_category_record_mm');
$tmpQB = $tmpCon->createQueryBuilder();
$rows = $tmpQB
->select('uid_foreign')
->from('sys_category_record_mm')
->where(
$tmpQB->expr()->in('uid_local', $tmpQB->createNamedParameter($categories, Connection::PARAM_INT_ARRAY))
)
->andWhere(
$tmpQB->expr()->like('tablenames', $tmpQB->createNamedParameter('tx_news_domain_model_news'))
)
->execute()->fetchAll();
if( is_array($rows) && count($rows) > 0 ){
foreach($rows as $row){
$newsOfCategory[] = $row['uid_foreign'];
}
}
}
May be someone can use that in the future or the will integrate that to the repository.