Empty resultset evaluation

Question

Hi, 
 I am new to Appian and in learning phase. I would like to know how do I treat empty resultSets while using using a!forEach combined with a!queryEntity 
 
 My requirements: 
 
 Query a table 
 When there are no results, return false 
 If there are results, iterate the results and return if the result set contains non blank items of a column

I had added an if condition in a!forEach expression. I am using fv!itemCount>0 condition which works fine only when there are valid results. it is not going into the false block when the resultset is emtpy. 
 How do i check a!queryEntity returns an empty entity/ data without any results? 
 
 Your help is much appreciated! 
 
 Please ignore any typos/syntax errors on the below snippet.

load(
local!localCollections: a!queryEntity(
entity: cons!MY_ENTITY,
query: a!query(
logicalExpression: a!queryLogicalExpression(
operator: "AND",
filters: {
a!queryFilter(
field: "myPK",
operator: "=",
value:6
),
ignoreFiltersWithEmptyValues: true
),
pagingInfo:a!pagingInfo(startIndex: 1, batchSize: - 1
)
),
fetchTotalCount: true

),
a!forEach(
items:local!localCollections,
expression : if(fv!itemCount>0,
rule!GBL_isNotBlank(index(fv!item, "status", null)),
true()
)
)
)

Selvakumar Kumarasamy · Answer

Hi ramkumars0001 , 
 The query entity will usually return the results in a data subset type. I could see that you're typically giving the data subset as the input to the forEach(). The function has the ability to operate on the data inside the data subset & if it has no data, then the function will not even call the expression defined. Hence you might not be getting the output. 
 Below code snippet might help you to return false if there are no data(this is one way, there are other ways too). a!localVariables(
 local!localCollections: a!queryEntity(
 entity: cons!MY_ENTITY,
 query: a!query(
 logicalExpression: a!queryLogicalExpression(
 operator: "AND",
 filters: {
 a!queryFilter(
 field: "myPK",
 operator: "=",
 value:6
 )
 },
 ignoreFiltersWithEmptyValues: true
 ),
 pagingInfo: a!pagingInfo(startIndex: 1, batchSize: 10)
 ),
 fetchTotalCount: true
 ),
 if(
 index(local!localCollections, "totalCount", 0) = 0,
 false(),
 a!forEach(
 items: local!localCollections,
 expression: if(
 fv!itemCount > 0,
 rule!GBL_isNotBlank(index(fv!item, "status", null)),
 true()
 )
 )
 )
) 
 But I'm still not getting your specific use case - whether it is to return a boolean array (or) list of items that are not null?

Acacio Barrado · Answer

Hi There, 
 You could try to add the following filter, that would help you to remove the null values: 
 a!queryFilter(
 applyWhen: not(rule!GBL_isNotBlank(ri!NO_BLANK_COLUMN)),
 field: "NO_BLANK_COLUMN",
 operator: "not null",
 value: ri!NO_BLANK_COLUMN
 ), 
 Hope that helps, 
 Regards, 
 Acacio B.

ramkumars0001 · Answer

Selvakumar Kumarasamy Thanks, this is exactly is what i am looking for. 
 
 Thank you for your time and help. Much appreciated.

Empty resultset evaluation

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