FileFieldAssembler::prepareRows

public function prepareRows(array $rowList): array
{
	if (empty($this->getColumnIds()))
	{
		return $rowList;
	}

	$fileIds = [];
	foreach ($rowList as $row)
	{
		foreach ($this->getColumnIds() as $columnId)
		{
			$value = $row['data'][$columnId] ?? null;
			if (is_array($value))
			{
				foreach ($value as $valueItem)
				{
					$fileIds[] = (int)$valueItem;
				}
			}
			elseif (isset($value))
			{
				$fileIds[] = (int)$value;
			}
		}
	}

	if (empty($fileIds))
	{
		return $rowList;
	}

	$this->preloadFiles($fileIds);

	return parent::prepareRows($rowList);
}