What does getTablesDataFromArray in the DataWriter do?

[Robust]

What does getTablesDataFromArray do? I don't really understand its purpose. The tables data is already given if you do getForumById, for example, so why do this?

e.g. from XenForo_DataWriter_Forum:

    protected function _getExistingData($data)
    {
        if (!$nodeId = $this->_getExistingPrimaryKey($data))
        {
            return false;
        }

        $forum = $this->getModelFromCache('XenForo_Model_Forum')->getForumById($nodeId);
        if (!$forum)
        {
            return false;
        }

        return $this->getTablesDataFromArray($forum);
    }

 

[Chris D]

A single DataWriter can support writing to, and returning data from, more than one table e.g. the user DW supports xf_user, xf_user_profile etc. and the forum DW supports xf_forum and xf_node.

That function arranges the data returned from the query (which may include data from more than one table via joins) into an array grouped by the table it came from.