[Digikam-users] What is being/will be done about the tags management problem?

[Andrew Goodbody]

On 19/02/13 18:01, jdd wrote:
> Le 19/02/2013 18:46, Gilles Caulier a écrit :
>
>> And definitively, this cannot be an introduce small project for
>> students, but a real GoSC 2013 project, because it's more complex that
>> i supposed in my previous mail.
>
> are there on this list people that needs merging of the tags in the
> database?

I'm not entirely sure but that merge may have been the result of a bug 
fix involving adding a new tag to multiple images that did not share the 
same set of initial tags.
https://bugs.kde.org/show_bug.cgi?id=264745

> if not it could be very easy to stop messing tags (the solution was
> given in the JFR mail).

Actually it does not address all the issues. When tags are renamed, 
moved or deleted then only the database is updated. For the issues that 
Jean-François mentioned to even matter in these cases there first of all 
needs to be a process that identifies all affected images and updates 
the tags for each image, be that in the image files or in the sidecar 
files. AFAIK at the moment this simply does not happen at all. It is not 
a case of merge vs replace and having to choose which one it should be. 
To me this is absolutely a bug. It is vital infrastructure that has 
never been implemented let alone been done wrong. It has nothing to do 
with external programs altering image metadata, it is simply internal 
house-keeping that must be done.

In implementing this process of updating the metadata for every affected 
image then there must be a choice made of how to keep the changes to the 
image metadata and the database metadata synchonised and then we need to 
pay attention to Jean-François' ideas. Although in this case there is 
another possibility. If it is possible to visit each image and use the 
knowledge of the actual operation that is in progress then only that 
operation could be applied both to the database and to the image file. 
In this case if the image file and database were out of synchronisation 
to start with they would still be out of synchronisation afterwards as 
well. Only the tags being moved, renamed or deleted would be affected. 
All other tags would not change.

However I am afraid that digikam has not been designed to be able to 
apply update operations to image metadata. I think that update 
operations are applied to the database and then all the database entries 
for that image are either written out or not. So implementing my idea 
above would not be simple.

Andrew