Value mapping functoid supressing string concatenate

Question

I have a string concatenate functoid which concatenates a street name and the street number. For this I have 2 value mapping functoids which both receive their value from the input file if it is not blank, as seen here:

In my test file, only the street name is given which has the street number. But when I test my map, it won't create the street address in the output file at all. If I try to remove the link from the street number value mapper, it works fine.

I'm not sure what causes this behaviour. Is the string concatenate being supressed in some manner, if some of it's input links do not return a value?

Answer 1

The script of that Functoid is:

public string StringConcat(string param0, string param1)
{
   return param0 + param1;
}

Then you have to check when the input parameter is null. The best option is add 2 more Value Mappings, but the condition the negation of the existing ones and the output an empty string.

Answer 2

It's best to do this with a Scripting Functoid because you will, almost surely, have some special cases to cover.

I've done this more times than I can remember, trust me ;)