topic Re: Attribute Assistant Expression help in Water Utilities Questions

Attribute Assistant Expression help

LarryPhillips — Thu, 15 Sep 2011 20:46:43 GMT

Where can I find documentation on what type of arguments work with the expression value method in the DynamicTable for the infrastructure editing toolbar's attribute assistant?

I'm having some trouble with data types among other things. One example looks like this:

...IIF([INSTDATE]="","NONE",YEAR([INSTDATE]))...

I get an error of wrong data type while this work fine:

...", YEAR INSTALLED " & YEAR([INSTDATE])...

I used the "" because I could not figure out the syntax for ISNULL.

I get alot of syntax errors not knowing what functions/operators work with the Expression Value Method.

Re: Attribute Assistant Expression help

MikeMillerGIS — Fri, 16 Sep 2011 11:12:05 GMT

After we translate the fields to values, we pass the expression to the MSScriptControl.ScriptControlClass object. I think you want to us the isNull expression, so like below:

IIF(isNull([FIELD]),TrueValue,FalseValue)

Re: Attribute Assistant Expression help

LarryPhillips — Fri, 16 Sep 2011 13:25:25 GMT

Row Info
        Row Number 1
        TableName: SWR_Manholes
        FieldName: UNITDESC
        ValueInfo: IIF(isNull([MHDPTH]),"UNKNOWN",[MHDPTH])
        ValueMethod: EXPRESSION
        On Create: 1
        On Change: 0
        Order: 6

      Checking for Subtype Restriction
      The Field in the Field Name is not found: value(25)
                  Trying: EXPRESSION
                  replace field: MHDPTH with a value
                  replace field: MHDPTH with a value
                  ERROR: evaluating the expression for feature in SWR Manholes with OID of 24849
                         Syntax error
                  Finished: EXPRESSION

After we translate the fields to values, we pass the expression to the MSScriptControl.ScriptControlClass object. I think you want to us the isNull expression, so like below:

IIF(isNull([FIELD]),TrueValue,FalseValue)

Re: Attribute Assistant Expression help

MikeMillerGIS — Fri, 16 Sep 2011 15:19:15 GMT

Can you download the beta and try that? I fixed a bug that might be the cause of your issue.

Re: Attribute Assistant Expression help

LarryPhillips — Fri, 16 Sep 2011 18:53:39 GMT

Ok, I have the Beta installed and tested.

The isNull still doesn't work, the same way it didn't work before. If there is a value it passes a "false" if the value is <null> I get a syntax error.

IIF([INSTDATE]="","NONE",YEAR([INSTDATE]))

First run results: INSTDATE=somevalue I get the year of that value! yeah.
First run results: INSTDATE=<null> I get "NONE"! yeah.
run results: INSTDATE=somevalue then set it to null I get a data type error. Boo!
run results: INSTDATE=<null> then set a date I get the year of that date! yeah!

One more issue, when I set a nonstring data type fields (ie; Double) ="" I get a data type error if it is null.

Here's to me wishing there was an emoticon beating it's head against the wall because thats how I feel.

Re: Attribute Assistant Expression help

MikeMillerGIS — Fri, 16 Sep 2011 19:48:44 GMT

You cannot set a non string field to an empty string. Even an empty string is a string. If you are trying to set a value as null, I am not sure you can. We would need to translate a value you entered as null to a true null value. Would you want use to translate <Null> to null?

Re: Attribute Assistant Expression help

LarryPhillips — Fri, 16 Sep 2011 20:29:29 GMT

What I am trying to do is populate a unit description field. A text field verbally describing the asset's attributes. The difficulty with this is that I need to say when I don't have attributes. i.e.; ASBUILT NONE, MANHOLE DEPTH UNKNOWN. As opposed to ASBUILT 05-1515, MANHOLE DEPTH 5.7FT.

So what I attempted to do was evaluate if the attribute had a value or not and then populate accordingly. Well this works fine if it's a new feature. But when I find that my manhole depth is incorrect because the invert was set to "0" and I "<null>" the data the attribute assistant fails.

And I was trying to use the ="" where I could because the isnull has a syntax error when the value IS NULL. I attempted to us Cstr() to force it to work too. Oh well.

Words are such a sorry example of actual work. 😞
I can only hope this explanation will help in the understanding of the previous post. 🙂

Re: Attribute Assistant Expression help

MikeMillerGIS — Mon, 19 Sep 2011 16:18:32 GMT

I posted an updated version that handles IsNull a little better. I tested you equation you sent me and it works if you remove the YEAR() part. A IIF statement in VB evaluated both true and false parts, so you cannot pass a null in and define a process on it.

Article explaining the IIF statement - http://msdn.microsoft.com/en-us/library/27ydhh0d(v=vs.80).aspx

Beta Version - http://forums.arcgis.com/threads/20000-Beta-Versions

Re: Attribute Assistant Expression help

LarryPhillips — Mon, 19 Sep 2011 19:48:55 GMT

Thanks so much!! The isnull works!

I also did not realize the iif statement evaluated both true/false parts. So now when I evaluate the is null I populate a string "SetFromSomeField" and then use the Replace() to set it, works with Year() too.

Run_order | Value_info
1] | [UNITDESC] & ", MH DEPTH " & IIF(isNull([MHDPTH]),"UNKNOWN","SetMhDpth")
2] | REPLACE([UNITDESC],"SetMhDpth",[MHDPTH] & "FT")

Re: Attribute Assistant Expression help

SamAdam — Tue, 14 Mar 2017 05:35:13 GMT

Hi Michael,

I know this is an old post , but is it possible in the current version of Attribute Assistant to set string or numeric fields to Null, if yes then how we can simply set the field to Null ?

The only reference I could find and it didn't work with me was below, I have tried VBNull and Null in the IIF below but also didn't work :

Attribute operations - Attribute Assistant | ArcGIS Solutions

To set values as null, use an empty string:
- Invalid: IIF([LOCDESC]=0, "<NULL>", [LOCDESC])
- Valid: IIF([LOCDESC]=0, "", [LOCDESC])

Re: Attribute Assistant Expression help

MikeMillerGIS — Wed, 15 Mar 2017 00:50:01 GMT

What is the log file reporting, reviewing the code <Null> should work, try without the " " around it

Re: Attribute Assistant Expression help

SamAdam — Fri, 17 Mar 2017 00:04:15 GMT

I have found that none of the following combinations of configurations sets the field to Null:

Expression : IIF(1 = 1 , Null, Null) => this results in an empty string instead of Null. Log file looks fine with no errors

Log File :

                  Trying: EXPRESSION
                  Checking to verify there is a field to store the expression
Expression to be eval: iif(1 = 1,Null,Null)
                  Setting Value to:
                  Finished: EXPRESSION

-----

Expression : IIF(1 = 1 , <Null>,<Null>) => this does nothing as it is considered syntactically incorrect as per log file:

Log File :

Trying: EXPRESSION
                  Checking to verify there is a field to store the expression
Expression to be eval: iif(1 = 1,<Null>,<Null>)
                  ERROR: evaluating the expression for feature in AA_VOne with OID of 1
                         Syntax error
                  Finished: EXPRESSION

-----

Expression : IIF(1 = 1 , "", "") => this results in an empty string instead of Null which doesn't align with the online reference in my previous post above. Log file looks fine with no errors:

Log File :

Trying: EXPRESSION

                  Checking to verify there is a field to store the expression
Expression to be eval: iif(1 = 1,"","")
                  Setting Value to:
                  Finished: EXPRESSION

----

Expression : IIF(1 = 1 , vbNull, vbNull) => this results in the value of the vbNull which is 1 string instead of Null. Log file looks fine with no errors

Log File :

                  Trying: EXPRESSION
                  Checking to verify there is a field to store the expression
Expression to be eval: iif(1 = 1,vbNull,vbNull)
                  Setting Value to: 1
                  Finished: EXPRESSION

-----

Expression : IIF(1 = 1 , <Null>,<Null>) => this does nothing as it is considered syntactically incorrect as per log file:

Log File :

                  Checking to verify there is a field to store the expression
Expression to be eval: <Null>
                  ERROR: evaluating the expression for feature in AA_VOne with OID of 1
                         Syntax error
                  Finished: EXPRESSION

Re: Attribute Assistant Expression help

SamAdam — Fri, 17 Mar 2017 00:04:30 GMT

After trying many combination , the correct way to set the field to null is what is mentioned in the documentation as 'Invalid' below !

You have to use (in the simplest case) Expression = "<Null>" . that will work with string or numeric field data type , and can also be used in IIF expression or any complex VBScript expression.

Empty sting as mentioned below will never set the field to Null, regardless of the data type of the field.

Attribute operations - Attribute Assistant | ArcGIS Solutions

To set values as null, use an empty string:
- Invalid: IIF([LOCDESC]=0, "<NULL>", [LOCDESC])
- Valid: IIF([LOCDESC]=0, "", [LOCDESC])