Filter Tool: 'Is not null' versus 'Contains'

Question

Hi,

I don't fully understand why in the example below the Filter Tool is not doing what is supposed to do. It must be a data type situation...

* What do I want: Something very easy. Filter out [Null] rows
* What did I Do?

1. Filter Tool > Basic Filter > Field 'Category' > Is not null > The result is blank

I changed to 'Contains' and it worked.

What I need to do is similar to this example, configuring the Basic filter to 'Is not [Null]'

Data source: Challenge #337

Thanks!

PanPP · Accepted Answer

Hi @alt_marsan

Make sure your data type is a string value when using the null or is not null option.

When using the filter tool, and using the "is not null" option, the false anchor will provide the null values.

You can always use the T or F anchor of the filter tool depending on what data you need.

alt_marsan · Accepted Answer

Hi @PanPP,

Thanks for your reply. I am very familiar with the anchors, also I previously tried all different types of String Data Type: String, V_String, V_WString, etc. Still nothing changed. Also , I run the workflow multiple times after each change. I'm puzzled by this issue...

martinding · Accepted Answer

Hi @alt_marsan ,

In this situation, the correct approach is indeed to use Contains.

The ISNULL() checks to see if the field's value is null (not existent or not).

For example, in the [listed in] field, ISNULL() can only filter out rows with no observations --> rows that appear as a [null] entirely. It won't actually check if 'international' is among the other listed categories or not.

Hope this helps

martinding · Accepted Answer

Please see the attached workflows as an example.