How to set the filter for a field (varchar, yes NULL ) with empty value in Query Editor

This is a long-known "bug" of sorts with the way a!queryEntity works (unfortunately); but there's a relatively easy workaround once you know it - a!queryFilter(field: "matnr", operator: "=", value: " ")  (that's an empty space). So you'd make a queryLogicalExpression() entry with the "OR" operator doing this *and* the "is null" operator check.

(I have no idea what you'd do, however, if you wanted to find entries where the value of the field = "one empty space", but whatever.)

I see, I was set it to value: "", no space character, it did not work. I just tried you way: value: " " (with a space character), seems it working, though feel it's kind weird.

Thank you very much for the information.

Interesting I'd never done this before - instead I've always used the "in" operator, which allows you to provide an empty string. That way, you'd still be able to distinguish between a true empty string and a space.

Here's an example:

filter: a!queryFilter(
  field: "text",
  operator: "in",
  value: {""}
)

For what it's worth, if you use synced records you don't need to do this - using the "is null" operator will return both explicit NULL values and empty string values

Interesting I'd never done this before - instead I've always used the "in" operator, which allows you to provide an empty string. That way, you'd still be able to distinguish between a true empty string and a space.

Here's an example:

filter: a!queryFilter(
  field: "text",
  operator: "in",
  value: {""}
)

For what it's worth, if you use synced records you don't need to do this - using the "is null" operator will return both explicit NULL values and empty string values

Hi Peter,

unfortunately the "is null" operator does NOT work for empty string, otherwise I would not post the question here.

Mike mentioned it's a long-known issue, I am hoping you can report this issue to Appian development team. hopefully they can fix it as it's really not a small problem, sometime have to do some trick thing.

Also another thing (mentioned in my post) is that even you explicitly set the value of a field as null in the input data, Appian's "write to data store entity" will still set the field data to empty string, that's also the reason I post this question here as I tried using "is null" operator is query editor, it does NOT return the record with empty string value.

regards,

Lin