Replace field with match or empty string?

[charlweed]

I want to “replace” a field with a string from the title is it is found, or an empty string if it is not.
I currently have mixed titles like:

Anne McCaffrey - Pern 10 - The Renegades of Pern
Generation Warriors
The Mystery of Ireta: Dinosaur Planet & Dinosaur Planet Survivors
Anne McCaffrey - Tsw 7 - Ship That Returned

I want to pick out “Pern 10” from the first example, and “Tsw 7” from the fourth example, and write them to the series field. How can I do this?

My current problem is that if there is no match for my group expression, the UI reports an “unmatched group” error, and refuses to proceed.
So how can I create a group that “always matches” but contains an empty string if it’s really not there?
Here is my current, erroneous expression,

(((P<author>[^-]*?)- )?((?P<series>\w+)\W*(?P<series_index>\d*)\s-))?(?P<title>.*)

The only field I want at the moment is \g<series>

Thanks!

[M. Northstar]

I joined the forums to ask about exactly this same problem, except that I'm using the Find&replace feature of the metadata editor... and if it doesn't find my group in a filename it returns the entire name instead of an empty string; i.e. my regex of

.*? \((.+?)-(\d+)\)

Applied to

• The Yellow Admiral
• Master and Commander (aubrey-1)
• Heart of the West

returns:

• The Yellow Admiral
• aubrey [1]
• Heart of the West

as the series.

Obviously this is sub-optimal, as in completely useless, so I'd be very grateful for some help.

[theducks]

Originally Posted by M. Northstar

I joined the forums to ask about exactly this same problem, except that I'm using the Find&replace feature of the metadata editor... and if it doesn't find my group in a filename it returns the entire name instead of an empty string; i.e. my regex of

.*? \((.+?)-(\d+)\)

Applied to

• The Yellow Admiral
• Master and Commander (aubrey-1)
• Heart of the West

returns:

• The Yellow Admiral
• aubrey [1]
• Heart of the West

as the series.

Obviously this is sub-optimal, as in completely useless, so I'd be very grateful for some help.

Series is a PITA
You need to do it as 3 passes.
Pass 1 sets JUST the series name
Pass 2 sets the Series_index

Pass 3 consumes the Series and Series index, leaving the remainder in the title