topic Defining a measure using another measure vs. using a var carrying the value of that measure in DAX Commands and Tips

Defining a measure using another measure vs. using a var carrying the value of that measure

AhmadBakr — Wed, 14 Aug 2024 12:39:50 GMT

Why the below measure is giving me the error:

"A function 'PLACEHOLDER' has been used in a True/False expression that is used as a table filter expression. This is not allowed."

chk RunWD =
VAR fdt = [chk FDate]
VAR Result =

CALCULATE(
COUNTROWS(DimWDates),
DimWDates[Date] > [chk FDate], --> returned error!
DimWDates[Date] <= TODAY()
)

RETURN Result

While the below is working fine, although they look the same!!! Just defined the measure as a variable!

chk RunWD =
VAR fdt = [chk FDate]
VAR Result =

CALCULATE(
COUNTROWS(DimWDates),
DimWDates[Date] > fdt, --> worked fine!!!
DimWDates[Date] <= TODAY()
)

RETURN Result

Re: Defining a measure using another measure vs. using a var carrying the value of that measure

Greg_Deckler — Wed, 14 Aug 2024 12:59:21 GMT

AhmadBakr Probably has something to do with CALCULATE and measures in filter clauses. What does this do?

chk RunWD = VAR fdt = [chk FDate] VAR Result = COUNTROWS( FILTER( 'DimWDates', [Date] > [chk FDate] && [Date] <= TODAY() ) ) RETURN Result

Re: Defining a measure using another measure vs. using a var carrying the value of that measure

AhmadBakr — Wed, 14 Aug 2024 13:16:07 GMT

Hey Greg_Deckler , thank you for your response.

I was thinking of the same approach, in fact 🙂.

It worked! no errors ✔️✔️✔️, same as defining a VAR.

However, this still does not answer the question: Why using the measure directly in the calculate filter argument returns an error!

I tried checking chatgpt and it gave me a strange explanation:

"In the first case, [chk FDate] is a measure and is directly used in the filter expressions. When you use a measure directly inside a CALCULATE filter argument, DAX expects it to be a valid True/False expression. However, measures often return scalar values rather than Boolean values, causing this error.

While in the second, the value of [chk FDate] is first stored in the variable fdt. Since fdt is now a scalar value (the result of the measure [chk FDate]), it can be safely used in the CALCULATE function as part of the filter expressions.

When you assign the result of a measure to a variable, you’re effectively converting the measure into a constant value that DAX can use as part of a logical comparison. Without this step, DAX tries to interpret the measure itself as a condition, which leads to the error."

chatgpt's answer means that DAX did not interpret the value of the measure, which is weird - if true.