TYPO3 / TYPO3.CMS

        $fromId = $fromRecord['uid'];

        // retrieve value from in-memory data-map

        if ($this->isSetInDataMap($item->getTableName(), $fromId, $fieldName)) {

            $fromValue = $this->allDataMap[$item->getTableName()][$fromId][$fieldName];

        } elseif (array_key_exists($fieldName, $fromRecord)) {

            // retrieve value from record

            $fromValue = $fromRecord[$fieldName];

        } else {

            // otherwise abort synchronization

            return;

        }

        // plain values

        if (!$this->isRelationField($item->getTableName(), $fieldName)) {

        $isSpecialLanguageField = ($configuration['config']['special'] ?? null) === 'languages';

        $fromId = $fromRecord['uid'];

        if ($this->isSetInDataMap($item->getTableName(), $fromId, $fieldName)) {

            $fromValue = $this->allDataMap[$item->getTableName()][$fromId][$fieldName];

        } else {

            $fromValue = $fromRecord[$fieldName];

        }

        // non-MM relations are stored as comma separated values, just use them

        // if values are available in data-map already, just use them as well