Typoscript DatabaseQueryProcessor - slide if field is empty - typo3

Question

I have a mm relation field in my page settings.
$myext_pages_fields = array(
'tx_myext_topofferitem' => Array(
'label' => 'Relation',
'config' => Array(
'type' => 'group',
'internal_type' => 'db',
'allowed' => 'tx_myext_topofferitem',
'MM' => 'tt_content_tx_topofferitem_mm',
'size' => '20',
'maxitems' => '99',
'show_thumbs' => '1',
'suggestOptions' => [
'default' => [
'searchWholePhrase' => 1
],
'pages' => [
'searchCondition' => 'doktype = 1'
]
],
)
),
);
\TYPO3\CMS\Core\Utility\ExtensionManagementUtility::addTCAcolumns('pages', $myext_pages_fields);
\TYPO3\CMS\Core\Utility\ExtensionManagementUtility::addToAllTCAtypes('pages', '--div--;Top Offers,tx_myext_topofferitem');
If the field is empty - the items of the next filled rootline page should be given.
To get the items i use the DatabaseQueryProcessor like that.
page = PAGE
page {
10 = FLUIDTEMPLATE
10 {
200 = TYPO3\CMS\Frontend\DataProcessing\DatabaseQueryProcessor
200 {
table = tx_myext_topofferitem
pidInList = root,-1
recursive = 99
selectFields = tx_myext_topofferitem.*
join = tt_content_tx_topofferitem_mm ON tt_content_tx_topofferitem_mm.uid_foreign = tx_myext_topofferitem.uid
where.data = field:uid
where.intval = 1
where.wrap = tt_content_tx_topofferitem_mm.uid_local=|
orderBy = tt_content_tx_topofferitem_mm.sorting
as = tx_myext_topofferitem_items
}
}
}
I tried to use this as where.data, but this does not work.
levelfield : -1 , uid, slide
(TYPO3 9LTS)

Answer 1

It seems that it's better to make use of nested data processing here. So first get a rootline menu and then fetch the items that belong to a specific page of that menu.
page = PAGE
page {
10 = FLUIDTEMPLATE
10 {
dataProcessing {
10 = TYPO3\CMS\Frontend\DataProcessing\MenuProcessor
10 {
special = rootline
special.range = 0|-1
special.reverseOrder = 1
as = rootline
dataProcessing {
10 = TYPO3\CMS\Frontend\DataProcessing\DatabaseQueryProcessor
10 {
if.isTrue.field = tx_myext_topofferitem
table = tx_myext_topofferitem
pidInList.field = uid
selectFields = tx_myext_topofferitem.*
join = tt_content_tx_topofferitem_mm ON tt_content_tx_topofferitem_mm.uid_foreign = tx_myext_topofferitem.uid
where.data = field:uid
where.intval = 1
where.wrap = tt_content_tx_topofferitem_mm.uid_local=|
orderBy = tt_content_tx_topofferitem_mm.sorting
as = tx_myext_topofferitem_items
}
}
}
}
}
}