Normally the following expression should do what you want. We loop to get a first list (coma separated) then within this list we loop and keep only the suffix and we finish by concatenating again the result.
Tried with multiple elements
I have kind of found my answer though it is kind of annoying and I wish there was a better one.
To get a choice box you have to use the FIELD MAPPER input parameter and then define your choices there. However keep in mind that these are actually numbers that need to be converted to strings.
The problem is however when you convert a number ...
I had a big of a facepalm moment, I realized I could make my expression more simpler because I knew STDK would be NULL except in those situations. I had to make the expression more similar:
I could reuse these columns for other point shapefiles created in this process:
CASE when standaardDekking IS NOT NULL THEN
string_to_array( "standaardDekking" ...
The problem was/is definitely with raster calculator.
So I overcame this problem by changing gdal's raster calculator with raster calculator provided by SAGA. The setup is a bit different, but overall it works.
There is one strange issue though, sometimes code won't shoot results, but when I close and open QGIS and run it again immediately, it works. So this ...
I could think in three ways to get around that.
1. Batch Process
You can do a more generic model and then run as batch process.
2. Creating a intermediate Model
You can create a model that only process the Field Refactor, and than use it just like any other process algorithm. PROs: By this way you just have to setup only one algorithm.
CONS: you'll have to ...