WXR import incorrectly handles comment ID's, Results in threading being lost

[DD32]

The Export'd WXR files & Import process contains the original Comment ID, and Comment Parent ID allready. However, Upon import, the Comment ID's are re-assigned, however the parent ID's are not.

The result is that the comment threading is lost entirely.

Eg: Previously comment 1234 was in reply to comment 1222, however, comment 1222 is now comment 22, but comment 1234 still has '1222' as its parent_id.

2 options are possible:

• Remapping the comment parent ID's
• Preserving the comment ID's

The only issue i see with preserving the comment ID's is that importing into another blog with comments allready could cause conflicts, which would require remapping of some comment ID's regardless.

[9100] is how we fixed this for posts.

Too big a job for 2.7. Let's shoot for early 2.8 with a possible backport to a 2.7 dot release.

Punting due to feature freeze. Reconsider with next release.

I am currently testing a patch that preserves the comment_IDs where possible. This solves most of the issues. I will attach the patch after some more testing.

With threaded commenting in core with 2.7, now more threading in the wild. Raising priority. Depending on 2.8 release status and nature of the solution should consider getting in 2.8 .

Patch

WXR File I used to test the patch

I'd like to get this in in 2.8, I think it's a pretty simple and solid patch which solves a major annoyance...

IRC discussion for reference:

[09:30] <jdevalk> basically threw all comments into an array, sort them by id, remapped the wxr id's to the new id's and attach the correct parent
[09:31] <jdevalk> also working on a plugin that let's you import wxr files that are on the server, so you're not capped by HTTP upload restraints
[09:31] <ddebernardy> I take it you tested before/after with your data already, no?
[09:31] <jdevalk> yes.
[09:33] <ddebernardy> patch's logic seems correct
[09:33] <jdevalk> yeah it's not too hard
[09:34] <ddebernardy> an alternative method, which might be more robust, could be re-key the comments array based on parents
[09:34] <ddebernardy> array ( comment_parent => comments )
[09:34] <ddebernardy> and then do a double foreach loop
[09:34] <jdevalk> not sure i follow? :)
[09:35] <ddebernardy> well, it would cover the case where a weirdo plays with his database
[09:35] <ddebernardy> and ends up with comment IDs in an order than hasn't much to do with the comments date or hierarchy
[09:35] <ddebernardy> but it's such an edge case that we can ignore it imo
[09:36] <jdevalk> yeah i think so too

Safe to commit imo.

can wait until 2.9

unless someone wants to try it...

per discussion in IRC

let's give the double array approach a try, just in case.

http://core.trac.wordpress.org/ticket/8019#comment:9

I want to test the patch but I get an error on WP and WPMU 2.8.4:

Parse error: syntax error, unexpected T_VARIABLE, expecting T_FUNCTION in .../wordpress.php on line 529

Is there something new? Would be nice if the bug can be fixed.

Sorry, my mistake.

It works now. Thanks.

Assuming the correct advice was provided, this fix didn't solve the problem according to this Forum thread:

 http://wordpress.org/support/topic/312843

Replying to michaelh:

Assuming the correct advice was provided, this fix didn't solve the problem

Retracting that statement as the patch wordpress.php.diff does in fact fix the threaded comment problem at 2.8.4:

 http://wordpress.org/support/topic/312843?replies=17#post-1225031

Is this good to go?

if we make the assumption that they're tossed in, in the correct order, it worked fine a few months back.

there were some talks of using a double foreach loop in the event they weren't. but it's mostly an improvement over the current patch.

Replying to azaozz:

Is this good to go?

I tested against current trunk. Works fine as import on an empty blog as well as when importing on a blog which already has post/comment ids provided in the import. This should cover most cases and all further items would be improvements to this patch.

Refreshed patch that applies against trunk. Needs testing.

(In [12301]) Preserve parentage when importing comments. Props joostdevalk. fixes #8019

I assume that blogs which already have imported content will have to delete and re-import their comments to receive any benefits from this patch?