Expression Evaluation Error: The a!queryFilter function has an invalid value for the "value" parameter. When the value of "operator" is "=" "value" must not be null or empty.

Question

a!queryEntity(
 entity: cons!D202301DIV_GRL_DSE_ENTITY_REQUEST_DETAILS,
 query: 
 a!query(
 filter: a!queryFilter(
 field:"requestId",
 operator:"=",
 value:ri!requestId,
 applyWhen: not(isNull(ri!requestId))
 ),
 pagingInfo: a!pagingInfo(
 startIndex: 1,
 batchSize: 50
 )
 ),
 fetchTotalCount: false
)
 
 I am facing this error when I'm opening one of my forms in my process model.

Mike Schmitt · Answer

assuming you're using a version of Appian that's modern within the past ~year (which i hope most people are by now), you shouldn't be using not(isnull()) for anything, but instead a!isNotNullOrEmpty() , as this catches more (though not strictly *all*) corner cases representing an empty value. Also it would be helpful to know whether you've troubleshot this in an Expression Rule editor with various values for ri!requestId to see whether you can recreate this issue there, or whether it's just on a form.