Attribute Assistant IIF conditional

[JoeBorgione]

I don't understand the IIF(condtional) expression syntax and I'm hoping someone can explain it a little better than the example at Attribute Assistant methods - Attribute Assistant | ArcGIS Solutions .

The basic syntax goes IIF(expression, truepart, falsepart).  In my simple mind, I read this as:

If the expression evaluates as true, return the truepart, and if it evaluates as false, return the falsepart.

I guess this isn't correct.

In my case, I am examining the field ROADTYPE to see if it is null.  If it is null, I would like to populate the field FULLNAME with the concatenated values of fields ROADNAME and ROADPOSTDIR.  If ROADTYPE is not null (which indicates it has a value), I want to populate the field FULLNAME with the concatenation of  ROADNAME and the existing value of ROADTYPE.  So in the Value_Info field of my DynamicTable, for the FULLNAME field I have:

IIF(isNull(ROADTYPE),[ROADNAME]&" "&[ROADPOSTDIR],[ROADNAME]&" "&[ROADTYPE]) but doesn't return anything...

Sometimes our streets are named, sometimes they are numeric.  If they are named, they get a type, if they are numbered, they get a post directional:

JOES LN

versus

4104 S

Jeff Ward​

[DanPatterson_Retired]

no experience, but I did notice that field names seem to be enclosed in square brackets, except for this part

isNull(ROADTYPE)   did you just try a simple case, assign "null" if true and "not null" if false or whatever the non-python syntax is

[AllisonMuise1 · Accepted solution]

Try this syntax:

IIF(isNull([ROADTYPE]),[ROADNAME]&" "&[ROADPOSTDIR],[ROADNAME]&" "&[ROADTYPE])

(added [] around the field name in the isNull() function)

Also - make sure that the Field Name field int he Dynamic Value Table points to the field where you want the results to be written.

[JoeBorgione]

Thanks Dan and Allison;  I'll check my brackets in the table; these tired eyes!

moments later-  you guys are both correct.  But since I don't do facial hair, I gave the correct answer to Allison... (Just kidding Dan...)