[BUGFIX] Avoid using null as array key in extbase Backend

Using `NULL` as array key is converted to an empty
string in PHP and is deprecated since PHP8.5.0,
honored with following `E_DEPRECATED` error:

  Using null as an array offset is deprecated,
  use an empty string instead

Extbase `\TYPO3\CMS\Extbase\Persistence\Generic\Backend` is
modified now to mitigate using `NULL` as possible array key
in following methods:

* `Backend::insertRelationInRelationtable()`
* `Backend::updateRelationInRelationTable()`
* `Backend::deleteAllRelationsFromRelationtable()`
* `Backend::deleteRelationFromRelationtable()`

Resolves: #108347
Releases: main, 13.4, 12.4
Change-Id: I0d3fdeac05f48a5164125d2671ffc02d1d050937
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/91911
Tested-by: Stefan Bürk <[email protected]>
Tested-by: Anja Leichsenring <[email protected]>
Reviewed-by: Christian Kuhn <[email protected]>
Reviewed-by: Stefan Bürk <[email protected]>
Tested-by: Christian Kuhn <[email protected]>
Tested-by: core-ci <[email protected]>
Reviewed-by: Anja Leichsenring <[email protected]>
Reviewed-by: Oliver Klee <[email protected]>

Author: sbuerk

typo3/sysext/extbase/Classes/Persistence/Generic/Backend.php

@@ -615,11 +615,16 @@ protected function insertRelationInRelationtable(
         if ($parentObject->_getProperty(AbstractDomainObject::PROPERTY_LOCALIZED_UID) !== null) {
             $parentUid = $parentObject->_getProperty(AbstractDomainObject::PROPERTY_LOCALIZED_UID);
         }
-        $row = [
-            $columnMap->parentKeyFieldName => (int)$parentUid,
-            $columnMap->childKeyFieldName => (int)$object->getUid(),
-            $columnMap->childSortByFieldName => $sortingPosition ?? 0,
-        ];
+        $row = [];
+        if ($columnMap->parentKeyFieldName !== null) {
+            $row[$columnMap->parentKeyFieldName] = (int)$parentUid;
+        }
+        if ($columnMap->childKeyFieldName !== null) {
+            $row[$columnMap->childKeyFieldName] = (int)$object->getUid();
+        }
+        if ($columnMap->childSortByFieldName !== null) {
+            $row[$columnMap->childSortByFieldName] = $sortingPosition ?? 0;
+        }
         $relationTableName = $columnMap->relationTableName;
         if ($this->tcaSchemaFactory->has($relationTableName)) {
             $row[AbstractDomainObject::PROPERTY_PID] = $this->determineStoragePageIdForNewRecord();
@@ -641,11 +646,16 @@ protected function updateRelationInRelationTable(
     ): bool {
         $dataMap = $this->dataMapFactory->buildDataMap(get_class($parentObject));
         $columnMap = $dataMap->getColumnMap($propertyName);
-        $row = [
-            $columnMap->parentKeyFieldName => (int)$parentObject->getUid(),
-            $columnMap->childKeyFieldName => (int)$object->getUid(),
-            $columnMap->childSortByFieldName => $sortingPosition,
-        ];
+        $row = [];
+        if ($columnMap->parentKeyFieldName !== null) {
+            $row[$columnMap->parentKeyFieldName] = (int)$parentObject->getUid();
+        }
+        if ($columnMap->childKeyFieldName !== null) {
+            $row[$columnMap->childKeyFieldName] = (int)$object->getUid();
+        }
+        if ($columnMap->childSortByFieldName !== null) {
+            $row[$columnMap->childSortByFieldName] = $sortingPosition;
+        }
         $relationTableName = $columnMap->relationTableName;
         $row = array_merge($columnMap->relationTableMatchFields, $row);
         $this->storageBackend->updateRelationTableRow($relationTableName, $row);
@@ -664,9 +674,10 @@ protected function deleteAllRelationsFromRelationtable(
         $dataMap = $this->dataMapFactory->buildDataMap(get_class($parentObject));
         $columnMap = $dataMap->getColumnMap($parentPropertyName);
         $relationTableName = $columnMap->relationTableName;
-        $relationMatchFields = [
-            $columnMap->parentKeyFieldName => (int)$parentObject->getUid(),
-        ];
+        $relationMatchFields = [];
+        if ($columnMap->parentKeyFieldName !== null) {
+            $relationMatchFields[$columnMap->parentKeyFieldName] = (int)$parentObject->getUid();
+        }
         $relationMatchFields = array_merge($columnMap->relationTableMatchFields, $relationMatchFields);
         $this->storageBackend->removeRow($relationTableName, $relationMatchFields);
         return true;
@@ -683,10 +694,13 @@ protected function deleteRelationFromRelationtable(
         $dataMap = $this->dataMapFactory->buildDataMap(get_class($parentObject));
         $columnMap = $dataMap->getColumnMap($parentPropertyName);
         $relationTableName = $columnMap->relationTableName;
-        $relationMatchFields = [
-            $columnMap->parentKeyFieldName => (int)$parentObject->getUid(),
-            $columnMap->childKeyFieldName => (int)$relatedObject->getUid(),
-        ];
+        $relationMatchFields = [];
+        if ($columnMap->parentKeyFieldName !== null) {
+            $relationMatchFields[$columnMap->parentKeyFieldName] = (int)$parentObject->getUid();
+        }
+        if ($columnMap->childKeyFieldName !== null) {
+            $relationMatchFields[$columnMap->childKeyFieldName] = (int)$relatedObject->getUid();
+        }
         $relationMatchFields = array_merge($columnMap->relationTableMatchFields, $relationMatchFields);
         $this->storageBackend->removeRow($relationTableName, $relationMatchFields);
         return true;