[wp-trac] [WordPress Trac] #17374: get_pages() with child_of forgets sort

[WordPress Trac]

#17374: get_pages() with child_of forgets sort
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 Reporter:  janfabry                |       Owner:
     Type:  defect (bug)            |      Status:  new
 Priority:  normal                  |   Milestone:  Future Release
Component:  Posts, Post Types       |     Version:  3.1.2
 Severity:  normal                  |  Resolution:
 Keywords:  has-patch dev-feedback  |     Focuses:
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Changes (by jessepollak):

 * keywords:  needs-patch needs-unit-tests => has-patch dev-feedback


Comment:

 OK, so it turned out that neither of my ideas were good ones. Both
 involved reimplementing parts of the MySQL search, which seemed like Bad
 Idea.

 Instead, I decided that I'd rewrite the {{{get_page_children}}}. In the
 current version, we do a top down recursive search to find all the
 children of {{{child_of}}}. The problem with this is that we get all the
 children at the same time, so they all get added to the new list at the
 same time — this messes up the sort that we had previously.

 In this patch, I reverse this so we do a bottom up search with a while
 loop to check whether a page has an ancestor with the ID {{{child_of}}}.
 If it does, we add it to the new list of pages to return. This maintains
 the sorted order because we're iterating through in sorted order and
 adding one page at a time. To make this search faster, we add all the
 pages to a dictionary so we can do O(1) lookup when traversing up the
 tree.

 I've also written a unit test that verifies the failed functionality and
 confirms the patch. I can write more, if we want.

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Ticket URL: <https://core.trac.wordpress.org/ticket/17374#comment:7>
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