WordPress Importer duplicates categories

[briancolinger]

The WordPress importer duplicates categories.
This only seems to affect child categories.
To reproduce, get an export file that has parent and children categories. Run the importer multiple times with the same file.
View the category screen under Posts->Categories, you should see duplicated child categories.

I've included a patch for the process_categories() method that fixes this by explicitly checking if each category_exists().
I've included the same patch for process_tags() method. Tags do not duplicate, but wp_insert_term() is called without checking if the tag exists.

[briancolinger]

patch for process_categories() and process_tags() methods

[markjaquith]

Thanks for the patch, but this needs some time to be reviewed, and we're too close to 2.9.

[scribu]

Related: #11080

[westi]

When we fix this I would like to add to the set of unit tests for import that we already have.

[demetris]

Maybe related: #12813. (Importer multiplies category with non-ASCII name)

[nacin]

Because of some extensive changes to the taxonomy API, is this still current as-is? I'm going to move this to 3.1 for the same reason it was moved to 3.0 -- we need some time to review it. Marking for early.

[mhhenn]

I am finding other problem regarding this subject. Seems that the parent-cat-slug is not transferred, it just look for parent-name. So if I have 3 main categories called "room1, room2 and room3" and each has a child-category with the same name but different slugs like "teacher1" and if every "teacher1" has a category-child with same name but different slug called "student1" when transferring the categories "student1" they are going to be located what seems to be randomly regardless the different slugs and not one "student" category for each "teacher1".

example:

room1
-teacher1(slug:room1-teacher1) -> student1 (slug:room1-teacher1-student1)

room2
-teacher1(slug:room2-teacher1) -> student1 (slug:room2-teacher1-student1)

room3
-teacher1(slug:room3-teacher1) -> student1 (slug:room3-teacher1-student1)

after importing the categories:

room1
-teacher1(slug:room1-teacher1) -> student1 (slug:room1-teacher1-student1)
-teacher1(slug:room2-teacher1) -> student1 (slug:room2-teacher1-student1)
-teacher1(slug:room3-teacher1) -> student1 (slug:room3-teacher1-student1)

room2
Empty -> Empty

room3
Empty -> Empty

[nacin]

(In [15961]) Importer and exporter overhaul, mega props duck.

Exporter overhaul:

• Add author information to export
• Greater usage of slug identifiers
• Don't export auto-drafts, spam comments, or edit lock/last meta keys
• Inline documentation improvements
• Remove filtering for now (@todo)
• Bump WXR version to 1.1, but remain back compat in the importer

Importer overhaul (​http://plugins.trac.wordpress.org/changeset/304249):

• Use an XML parser where available (SimpleXML, XML Parser)
• Proper import support for navigation menus
• Many bug fixes, specifically improvements to category and custom taxonomy handling
• Better author/user mapping

Fixes #5447 #5460 #7400 #7973 #8471 #9237 #10319 #11118 #11144 #11354 #11574 #12685 #13364 #13394 #13453 #13454 #13627 #14306 #14442 #14524 #14750 #15055 #15091 #15108.

See #15197.