topic Re: Attribute Assistant: Generating Null Values in State & Local Government Questions

Attribute Assistant: Generating Null Values

PhilWatson — Tue, 23 May 2017 20:05:47 GMT

I am using the Attribute Assistant tool to automatically generate values for certain fields using the Value Method FIELD_TRIGGER. I'm running into trouble when I want to use FIELD_TRIGGER to change the value of a field to be null. I have no problems writing a rule that generates a regular string or number value, but I can't figure out how to generate a null value.

When I use the Value Info of "Field Value|Field to Change|<Null>", it will put "<Null>" into any string fields I write the rule for, but I don't think this is a true null value because it doesn't work on number or date fields. I have tried countless variations on <Null> (<null>, "<Null>", null, isNull, etc) and none of them work.

After reading the documentation on Attribute Assistant, it looks like FIELD_TRIGGER might only return a number or string value. Has anyone figured out how to return true null values for fields using the attribute assistant?

You can see my specific rule in the attachment.

Re: Attribute Assistant: Generating Null Values

IanMurray — Tue, 23 May 2017 21:51:40 GMT

You probably need to use a None, not a NULL.

http://pro.arcgis.com/en/pro-app/tool-reference/data-management/calculate-field-examples.htm#ESRI_SECTION1_DFE39ACAD4144118AF066C6F2856197F

See last example.

(I know nothing about Attribute Assistant, but this seemed relevant)

Re: Attribute Assistant: Generating Null Values

PhilWatson — Wed, 24 May 2017 12:09:34 GMT

Thanks for the suggestion, although it didn't work. Attribute Assistant is a strange beast. There are a few instances where it reacts to VB syntax, but in this case, the value info field seems to be treating everything as straight text or numbers, not code.

Re: Attribute Assistant: Generating Null Values

PhilWatson — Wed, 24 May 2017 12:20:30 GMT

Michael Miller‌ is there any plans to introduce the ability to add null values? I came across an old thread where you considered adding the ability to use FIELD_TRIGGER for dates https://community.esri.com/thread/62983

Re: Attribute Assistant: Generating Null Values

MikeMillerGIS — Wed, 24 May 2017 12:23:57 GMT

You can use Expression to add null values.

Re: Attribute Assistant: Generating Null Values

PhilWatson — Wed, 24 May 2017 13:16:16 GMT

Thanks for the tip. I was able to accomplish getting a null value using this in the Value Info field: IIF([STATUS]=2,"<Null>",[DIAMETER])

I have the rule set to run on attribute change, so it is a bit weird that as long as the expression rings true it will constantly overwrite any changes I attempt to make. I was originally hoping to use FIELD_TRIGGER because it only runs at the moment the specific field is changed. EXPRESSION will run anytime I change any field, as long as the expression is valid. I guess I could move it to manual-only. I will have to play with it and see what works best.

Thanks,

Phil

Re: Attribute Assistant: Generating Null Values

MikeMillerGIS — Wed, 24 May 2017 13:41:36 GMT

I see, would not be hard to extend field trigger to set <Null> as null

Re: Attribute Assistant: Generating Null Values

MikeMillerGIS — Wed, 24 May 2017 13:44:38 GMT

I made the change in the source already, just need to test and I can push it to a preview build for you to try out.

Enhancement - Field Trigger - Support setting null · Issue #243 · Esri/local-government-desktop-addins · GitHub