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Bug Alert! How SELECTEDVALUE and HASONEVALUE Functions Can Upset You?

I've found a bug the other day by chance. When I searched about it, I've found out that it's an unsolved issue for years. If there's an issue that hasn't been solved for years, it definitely deserves a post, even a name. In my opinion, bugs should be named after their discoverers.  So here I am, with my bug. 

Before I get to the point, I'd like to clarify what the HASONEVALUE function does. Microsoft says: 'Returns TRUE when the context for columnName has been filtered down to one distinct value only. Otherwise is FALSE.' This function is not very intuitive because of its confusing name. Think it more like hasonefilter. It returns TRUE if the column is filtered by only one value. 


The measure called time you see below calculates this: If nothing is selected, print "Choose Date" if zero is selected print "Today", if null is selected print "Blank", otherwise extract the selected number as the number of days from today's date. 

When I select zero on the slicer, instead of showing today's date, it prints 'Choose Date' like nothing is selected. What's wrong? Why Power BI prints 'Choose Date' like nothing is selected? Thinking maybe there is a problem with some other part of the measure, I've decided to test it solo. 

This measure returns true if only one thing is selected, otherwise, it returns false.


Looks like nothing is wrong with anything other than the function itself. This is definitely a bug. And it happens only if I have a blank value in my column. It returns true if I don't have a blank.


Before I get to the problem with SELECTEDVALUE function, I need to explain what  SELECTEDVALUE function does. Microsoft says: 'Returns the value when the context for columnName has been filtered down to one distinct value only. Otherwise returns the alternate result.' To put it simply: if I select one thing only, it shows the only thing I selected. If I select many or nothing, it shows the alternate result which I'm going to determine.



This measure is supposed to show the selected value from the slicer if I select only one value. If I select many values or nothing at all. It's supposed to print "Select Day"

The computer says No! Looks like with SELECTEDVALUE function doesn't identify the selection as single if there is a blank in my column. I have tested it without having a blank and again it worked just fine. 

This is an issue for almost 4 years and nothing has been done about it so far. Maybe it wasn't reported before and the Power BI team is not aware of it. I don't know if that's the case but I'm definitely going to report it myself.
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