DataHandler structure for creating parent/child record relations

Question

I'm trying to create nested record structures using TYPO3's DataHandler data structures (tested with TYPO3 v7). However relations are not created as expected. Consider the following data structure:

        $data = array(
                'sys_category' =>
                        array(
                                'NEW_1' =>
                                        array(
                                                'title' => 'Category 1',
                                                'pid' => $pid,
                                        ),
                                'NEW_2' =>
                                        array(
                                                'title' => 'Category 3',
                                                'pid' => $pid,
                                        ),
                                'NEW_3' =>
                                        array(
                                                'title' => 'Category 2',
                                                'pid' => $pid,
                                        ),
                                'NEW_4' =>
                                        array(
                                                'title' => 'Category 1.1',
                                                'pid' => $pid,
                                                'parent' => 'NEW_1',
                                        ),
                                'NEW_5' =>
                                        array(
                                                'title' => 'Category 1.2',
                                                'pid' => $pid,
                                                'parent' => 'NEW_1',
                                        ),
                                'NEW_6' =>
                                        array(
                                                'title' => 'Category 3.1',
                                                'pid' => $pid,
                                                'parent' => 'NEW_2',
                                        ),
                        ),
        );

This gives the following result in the database:

uid title           parent
1   Category 1      0
2   Category 3      0
3   Category 2      0
4   Category 1.1    0
5   Category 1.2    0
6   Category 3.1    0

Note the "0" value for all "parent" fields. Why is it that the "NEW_*" values are not interpreted for the "parent" fields set in the data structure?

Answer 1

As mentioned in a comment above, the situation changed between TYPO3 6.2 and 7.6. The difference lies in \TYPO3\CMS\Core\DataHandling\DataHandler::processRemapStack(). Starting with TYPO3 7.6, it checks if the "NEW*" placeholders contain a low dash (_). If yes, the placeholder is split on that character and the first part of the string is considered to be the related table name.

This is a change from before, where the low dash had no special meaning. Indeed, the documentation mentions examples using a low dash.

So the above code works fine with just removing the low dash from all the placeholders.

Answer 2

As far as I see only the pid-value is checked for the "NEW"-keyword. But you could use some of the included hooks for enabling the assignment for "parent" too.

EDIT: I'm referring to TYPO3\CMS\Core\DataHandling\DataHandler::process_datamap()