[digiKam-users] Hierarchical tags, how are they stored?

[woenx]

Thanks for the reply.

for the sake of simplicity, let's just focus on lighroom's XMP metadata:

lr:
        hierarchicalSubject = Canada|Ontario|Toronto

So I have moved pictures that had

        hierarchicalSubject = Ontario|Toronto

where some of them were: 

    [ ] Ontario
        [x] Toronto

and some were:

    [x] Ontario
        [x] Toronto

(I don't mind, as long as they appear in the hierarchy).

Then, I created a new root tag called "Canada" (e.g. because I have pictures
from Quebec, and I want to incorporate everything into the "Canada" tag). So
on the tag tree I drag "Ontario" over "Canada". I get warned that xxx
pictures will be modified, etc, that's fine (but the number is lower than
the number of pictures that should be affected). Anyway, the new hierarchy
should look like this:

lr:
        hierarchicalSubject = Canada|Ontario|Toronto

Pictures that contained 
   
 [x] Ontario
      [x] Toronto

have been successfully updated and incorporate the full hierarchy in the xmp
metadata ("hierarchicalSubject = Canada|Ontario|Toronto"). But pictures that
just contained

[ ] Ontario
    [x] Toronto

were not updated, and the metadata looks like this "lr: hierarchicalSubject
= Toronto". However, selecting any of these pictures and manually
"Item/Write metadata to file", writes the full metadata including lr:
hierarchicalSubject = Canada|Ontario|Toronto. So I personally think this is
a bug where the database and the xmp metadata are out of sync, and all the
pictures included in the hierarchy should have been automatically updated
with the new metadata.



Wait, but there is more. Let's place one of the pictures with just "lr:
hierarchicalSubject = Toronto" in a new folder, and tell digikam to start a
new database in that folder and just scan this picture. My common sense
tells me that there this hierarchy will be created:

[x] Toronto

Ok, makes sense. And now let's add a second picture, one with the full
metadata containing "lr: hierarchicalSubject = Canada|Ontario|Toronto". My
common sense tells me this will happen:

[x] Canada
    [x] Ontario
        [x] Toronto
[x] Toronto

But instead, I get this:

[x] Canada
    [x] Ontario
        [x] Toronto

So, the full hierarchy has been recreated correctly! How does digikam know
that the pictures just containing the "Toronto" tag, without hierarchy,
should be placed within Canada/Ontario?



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