topic Re: Follow up to Null versus Not Null in Pro in ArcGIS Pro Questions

Follow up to Null versus Not Null in Pro

JoeBorgione — Mon, 02 Apr 2018 15:11:08 GMT

Last week I ran into some confusion when trying to use a FieldName is not null expression. See https://community.esri.com/thread/211900-arcgis-pro-select-by-attribute-is-not-null .

There were a number of records that had the string '<Null>' entered as the value which threw me off my game considerably. I talked to the data owner and he jumped on the problem immediately making the proper corrections.

Today I looked at the data again: it's a feature layer that is published from an enterprise geodatabase feature class to our local portal: the data owner made the edits to the e-gdb feature class. Now when I look at the data via the Select by Attribute tool in Pro, I still see <Null> listed as a value. The expression:

Reach ID is Equal to <Null> fails as it should

while Reach ID Is Null works, as it should

and Reach ID Is Not Null works as it should

However I still see an issue with the way Pro displays string field values with out quotes: the list displays <Null> as a valid value. After last week's foray, I still would consider this a six character string. ( <,N,u,l,l,>), but it isn't.

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Dan_Patterson‌

Re: Follow up to Null versus Not Null in Pro

DanPatterson_Retired — Mon, 02 Apr 2018 15:20:27 GMT

I can only speak for languages that implement the concept of 'null'-ness or 'none'-ness

It is either null, or it isn't (ie python is one)

Casting it to a string so it shows '<null>' is just pure evil, confuses people with <null>

I hate any concept of null/none that is not an obvious expression of an impossible value, whether it be text, float or integer. This distinguishes real valid values from a total lack of an observation.

It makes people complacent. We will blunder on regardless of how long we have been programming. -999 was good enough at one time.

'nuff said

Re: Follow up to Null versus Not Null in Pro

JoeBorgione — Mon, 02 Apr 2018 15:27:40 GMT

It is either null, or it isn't (ie python is one)

Casting it to a string so it shows '<null>' is just pure evil, confuses people with <null>

Absolutely.

My problem is ArcGIS Pro does not make the distinction when offering 'values' in the selection tool like ArcGIS ArcMap does.

Re: Follow up to Null versus Not Null in Pro

JoshuaBixby — Wed, 04 Apr 2018 21:45:13 GMT

Joe, when using the Select Layer by Attribute tool with GDBs (not sure about AGOL/Portal layers), if you see <NULL> in a Values list for a string field, then you have <NULL> written out as text. The Values list never populates NULL (if it is truly NULL and not NULL written as text), so if you see it in their, it is a string.

I assume AGOL/Portal layers are the same, but I will have to check and post back.

Re: Follow up to Null versus Not Null in Pro

JoeBorgione — Wed, 04 Apr 2018 22:34:44 GMT

They are in fact text- the data owner hadn't fixed them. But.... I tried a selection where FieldName is Equal To <Null> and it failed. I can't remember now what the error was and now the owner has fixed the data, so <Null> no longer appears in the list. And that's all that matters to me at this point!