Quick Q: I've seen some other questions around this but not quite what I'm looking to do. Hopefully it's simple.

I have a series of lines that I want to join together using the LineJoiner transformer. So far so good and this works nicely...BUT...each polyline has an ID unique to that line segment.

I would like to use the LineJoiner to chain polylines together but I want to keep the combined attributes (ID) as a list associated with the elements (either comma seperated or as a seperate list). The reason is that at the end I'd like to be able to see a polyline and know it's been made up of ID's 2,3,4.

Is this possible in FME or do I need to look elsewhere?


1 Answer 1


That should be possible by using the Generate List option. I've looked back as far as 2016 and that parameter was available then, so unless you have a really old FME you should have it available to you.

Basically just check the box for Generate List. This is how it looks in FME 2019:

enter image description here

Note: The transformer name changed from LineJoiner to LineCombiner (to avoid confusion with database joiner type transformers).

With that list you can either patch it all together (ListConcatenator) or separate it into separate records (ListExploder)

  • 1
    Ah brilliant - many thanks. It turns out I didn't need it to be concatenated into a comma seperated list. I added a counter and loaded the results into a DB so I have the LineJoiner "ID" and then a list of the polyline IDs that were joined. I had to use ListExploder after the LineJoiner. Worked like a charm. Many thanks for the quick response and help.
    – user137468
    Feb 22, 2019 at 12:05

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