Unable to Use RELATED in a measure

Question

This is a peculiar issue I'm facing -

Lets say I've a following Table A -

UniqueID	User
A1	Adam
A2	Dim
A3	Jo
A4	Bill

and Table B -

UniqueID	RelatedID	Type
B1	A2	Email
B2		Email
B3	A3	Note
B4	C5	App

They have an Active Relationship- (Table A[UniqueID] 1:N Table B[RelatedID]).

My Slicer is Based of - TableA[User] and I wanted a count of only those IDs to show up which had a user in Table A

I Made the Following Measure -

EmailCount = 
Var _eCount = 
CALCULATETABLE(TableB, TableB[Type] =  "Email" && TableB[RelatedID] <> BLANK() && NOT(ISBLANK(RELATED(TableA[User]))))

Return COUNTROWS(_eCount)

I'm getting the following error -

The column 'TableA[User]' either doesn't exist or doesn't have a relationship to any table available in the current context

Not sure what I'm doing wrong here.

Answer 1

EmailCount = 
Var _eCount = 
CALCULATETABLE(TableB, 
FILTER(TableB, 

TableB[Type] =  "Email" && TableB[RelatedID] <> BLANK() && NOT(ISBLANK(RELATED(TableA[User])))))

Return COUNTROWS(_eCount)

Explanation:

Your original expands as follows. i.e. ALL() can only cover columns from the same table and there is no Table A to reference. The FILTER in my solution above permits access to the expanded table (in this case both tables)