Concatenate strings with null values doesn't work as expected

[iomicifikko]

1. Concatanate strings using the sum operator gives always null as output if at least one string is null
2. The join() function doesn't output null values as expected

Examples

The following code
with("banana", fruit1, with (null, fruit2, fruit1 + ", " + fruit2))
returns
null
instead of
banana,

The following code
["banana", null, "apple"].join(", ")
returns
banana, apple
instead of
banana, , apple

Reference

https://github.com/OpenRefine/OpenRefine/wiki/Recipes#merging-several-columns

Versions

• Operating System: Windows 11
• Browser Version: Chrome 123.0.6312.106 (Build ufficiale) (a 64 bit)
• OpenRefine: 3.7.9 with builtin java

[iomicifikko]

Other strange behaviors of the JOIN() function with blank / null / empty string values

Image 1

Image 2

Image 3

In my opinion the occurencies of the separator character (the pipe, in the three images above) inside the final string should always be equal to the length of the original array minus one (3 -1 = 2, in the three images above).
The user can easily exclude if necessary any particular values (blanks, nulls...) using the FILTER function on the array before using the JOIN function.

[tfmorris]

Thanks for the reports. If I could make a request, it would make it much easier to reproduce/fix the issues if you were to:

• provide the GREL expression and expected result as text rather than an image
• strip the examples down to the minimum which reproduces the issue (for example, it isn't clear in your last set of examples with the problem is with join() or forEach()
• put different problems into separate bug reports - this seems to be an amalgam of issues with string concatenation (or with?), join, and, perhaps, forEach. The additional complexity of having them altogether will make it harder for someone to tackle any of the issues.

OpenRefine's treatment of null values has been a little bit uneven (and evolving), as I mentioned in your #3290, which seems like it has a fair bit of overlap with this.