Problem moving a hierarchy of tags

[Boudewijn]

On maandag 24 april 2017 01:19:04 CEST Louis A. Turk wrote:
> I'm having the same problem described here:
> 
> https://photo.stackexchange.com/questions/82749/moving-a-hierarchy-of-tags-a
> -tag-with-subtags-around-in-digikam

As in:  

> Marcus C.asked Sep 11 '16 at 15:12 (stackexchange):
> > I re-organized whole tag trees and then deleted the original root tags.
> > Upon re-opening Digikam that root tags were gone, of course, but the 
> > trees that I had moved had disappeared as well. 

> Is there a solution to this problem?

I think it is important first to find out why things occur to happen 
differently from expected. As I understand: 

1. There is the current tag tree, TT, with subtrees TTa and TTb, and below 
that TTa1 and TTa2. 
2. Tags are assigned to photos. Some photos (P) are assigned one tag, other 
photos other tags and so on. For example, P1(TTa1), P2(TTa2), P3(TTa2+TTb)
3. The tag tree is reorganised. TTa2 is moved to TTb, to become TTb2. TTa1 
becomes a new top level tag TTc.
4. Each picture still got its assigned tag as stated above (P1(TTa1), 
P2(TTa2), P3(TTa2+TTb), etc)
5. Tags from TTb2 are not assigned to any photo. Same goes for TTc
6. Sub tree TTa is removed

The important step is 5. The problem is not in the moving of the hierarchy, 
but in the lack of applied tags to photos. 

The way I reorganize tags:

1. Create a new tag TTc that replaces TTa1
2. Select all photos with TTa1
3. Apply TTc to all those photos
4. Remove TTa1 from all those photos
5. Upon viewing the contents of TTa1, there is nothing left (as all photos 
have this tag removed)
6. Upon viewing the contents of TTc, all photos that used to have TTa1 are 
shown. 

Good luck! 

Best regards,

Boudewijn