After upgrading from 7.9.3 to 7.9.18, I’ve been seeing some errors in our Expression code.
“Error evaluating tag: Expression left operand is null.”
We have a UDT with several query tags, sometimes there are no rows in the dataset.
In an expression tag we have:
sum({[.]SQLVolumeDS}, "converted_value")
+
sum({[.]SQLDilutionsVolDS}, "converted_value")
+
sum({[.]SQLTranserVolDS}, "converted_value")
I tried adding error handling but try(sum()) still returns null instead of zero, causing an error:
try(sum({[.]SQLVolumeDS}, "converted_value"), 0)
+
try(sum({[.]SQLDilutionsVolDS}, "converted_value"), 0)
+
try(sum({[.]SQLTranserVolDS}, "converted_value"), 0)
Any suggestions for getting this tag to calculate the total, even if any one of the datasets are empty?