[digiKam-users] Odd problem with tags, a sort of 'ghost' tag

Gilles Caulier caulier.gilles at gmail.com
Thu Sep 27 18:39:58 BST 2018

2018-09-27 18:10 GMT+02:00 Chris Green <cl at isbd.net>:

> meku <digikam at meku.org> wrote:
> > [-- text/plain, encoding quoted-printable, charset: UTF-8, 42 lines --]
> >
> > That the image shows up when using the left sidebar but not the tags
> filter
> > suggests to me that your Tags tree is in an inconsistent state.
> >
> > Depending on your Digikam version and database backend this can happen
> when
> > creating or deleting Tags. I haven't confirmed if the Digikam maintenance
> > tool will correct this inconsistency, personally I use a script that will
> > rebuild the Tree when this happens.
> >
> Yes, I suspect that tag handling is not as robust as it might be.
> What does your "script that will rebuild the Tree" actually do?
> Going on from that can anyone tell me which Tag modification actions
> write to the database and which write to the image metadata?  ... and
> why doesn't Digikam always write to both?

This is the legacy of the project (started in 2001, don't forget).

Some people want store in both, some other just in database (and never
touch original image).

The last one is the default workflow.

The complexity of the metadata hub (it's called like this in source code)
is to be able to handle all case with tags, written from DK, outside, from
another application (welcome interroperabilty), manage all kind of file
formats, handle XMP side car, must support multi-threading.

All low level operations are delegate to Exiv2 library.

For tags, and multiple selection of items with different tags already
assigned, we need to process a good merging, without lost anything,
depending of tags list changes.

The maintenance is also tedious, especially to synchronize DB to image and

So, if you think that "tag handling is not as robust as it might be", well
you welcome to take the train in source code and to improve it. The game is
not so simple to manage, if you list all input conditions and all output
states from the box.

Gilles Caulier

> --
> Chris Green
> ยท
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