How to search for pictures with a specific Xmp.dc.creator

[johannes.lists+mail.kde.org at tannenhof-imshausen.de]

Hello,

I use digikam to manage images from different photographers and use 
Caption/Tags -> Information -> Template to set the correct author name 
for every image.
(BTW, I don't understand why I have to add a new template every time if 
I just want to add an  Author's name to an image…)

So, now I want to search for an image I only know it's creator. But 
searching for the name will not show any image.  Only when the name is 
present in file name, a tag, caption or title.

How can I search for Xmp.dc.creator?


I'm using digikam Version 4.12.0 on Ubuntu 16.04.2.


Thank you very much,
Johannes