How to parameterize a column for aggregation in Power BI desktop? - group-by

Question

I have users who would like to be able to modify what columns a table aggregates by. My issue is that I seem unable to do this in Power BI. I basically want to be able to do the following in SQL:
SELECT
<OrgLevel1>,
<OrgLevel2>,
SUM([Revenue])
FROM [Data]
GROUP BY
<OrgLevel1>,
<OrgLevel2>
;
where the user can change <OrgLevel1> and/or <OrgLevel2> to be any of { "(All)", [Department], [Product] }.
The issue may be related to this post: https://community.powerbi.com/t5/Desktop/Calculated-Column-Table-Change-Dynamically-According-to-Slicer/m-p/655991#M314800
Here's a link to a workbook that illustrates this issue, TestParameterizeGroupby.pbix (hosted by Google Drive). I've also included field definitions below with screenshots. Thanks for any help.
TestParameterizeGroupby.pbix
Link: TestParameterizeGroupby.pbix (hosted by Google Drive)
Problem
[Org Level 1] and [Org Level 2] fields are not recalculating from the users' selection. Only the default values are shown.
Expected result in table
"Org Level 1", "Org Level 2", "Revenue"
"(All)", "(All)", 28
Note
The purpose is to have parameterizable organization level fields so that the report user can aggregate by all, department, product, or both in either order.
Table and column definitions
'Data' = DATATABLE(
"Department",
STRING,
"Product",
STRING,
"Revenue",
DOUBLE,
{
{"DeptA", "ProdX", 5.0},
{"DeptA", "ProdY", 6.0},
{"DeptB", "ProdX", 10.0},
{"DeptB", "ProdY", 7.0}
}
)
'Data'[Org Level 1] = SWITCH(
'Org Level 1 Parameter'[Org Level 1 Parameter Value],
0,
"(All)",
1,
[Department],
2,
[Product]
)
// Problem: [Org Level 1] and [Org Level 2] fields are not recalculating from the users' selection. Only the default values are shown.
'Org Level 1' = DATATABLE(
"Org Level 1",
STRING,
"Org Level 1 Parameter",
INTEGER,
{
{"(0) (All)", 0},
{"(1) Department", 1},
{"(2) Product", 2}
}
)
'Org Level 1 Parameter'[Org Level 1 Parameter] = GENERATESERIES(0, 2, 1)
'Org Level 1 Parameter'[Org Level 1 Parameter Value] = SELECTEDVALUE('Org Level 1 Parameter'[Org Level 1 Parameter], 1)
Table 'Org Level 1' has a 1-1 relationship with 'Org Level 1 Parameter' on column [Org Level 1 Parameter].
The user selects the value for 'Data'[Org Level 1] by selecting the value for 'Org Level 1'[Org Level 1].
Tables and columns for [Org Level 2] are defined in the same way as [Org Level 1].
Screenshots
Report view:
Data view:
Model view:
Cross-reference to post in Power BI forum:
Power BI Forum: How to parameterize a column for aggregation

Answer 1

One solution to this is to add two list values parameters and use their values in Power Query M code to modify the database query. Lets assume that you have a table Data with columns Department, Product and Revenue. For simplicity I will add one more column, named Dummy Column, with all rows having the same value (e.g. null). I will explain why later in this post. So the table looks like this:
Then in your report specify a query when adding this table to your model (lets assume we will import it, but in general you can do this in DirectQuery too):
Now if you look the M code you will see the above query there:
Source = Sql.Database(".", "StackOverflow", [Query=" select ....
Now define couple of parameters, that the end-user can use to select how the data should be aggregated. Lets name them Level 1 and Level 2:
The value of a parameter can be used in M by parameter name, and & is used to concatenate strings. So if there is a parameter Name with value Samuel, the expression "Hello, " & Name & "!" will be evaluated as Hello, Samuel!. The idea is to check the value of our parameters and modify the database query accordingly.
In the select part, we will replace the name of the field selected, or we will put '' (empty string) in case of <All> (I surrounded parameter values with brackets to be more easily to distinguish parameter values from database field names). So the expression should look like:
"select " & (if #"Level 1" = "<Department>" then "Department" else ..." (and so on)
Because there is a space in our parameter's name, we need to surround it with #" and ", so Level1 can be referenced simply as Level1 in the code, but Level 1 becomes #"Level 1".
The group by part is a bit trickier. We should add a comma between field names, add or not field name, or even omit the group by at all (in case both parameters are set to <All>). To simplify this, I added one dummy column, with all rows having the same value (e.g. null) and always group by this column. This way building the group by clause is way more simpler - in case the parameter value is not <All>, we should add , fieldname. So the code could look like this:
"group by DummyColumn" & (if #"Level 1" = "<Department>" then ", Department" else ..." (and so on)
So the final M code is this:
let
Source = Sql.Database(".", "StackOverflow", [Query="select#(lf) " & (if #"Level 1" = "<Department>" then "Department" else if #"Level 1" = "<Product>" then "Product" else "''") & " as [Org Level 1]#(lf) , " & (if #"Level 2" = "<Department>" then "Department" else if #"Level 2" = "<Product>" then "Product" else "''") & " as [Org Level 2]#(lf) , SUM(Revenue) as Revenue#(lf)from Data#(lf)group by DummyColumn" & (if #"Level 1" = "<Department>" then ", Department" else if #"Level 1" = "<Product>" then ", Product" else "") & (if #"Level 2" = "<Department>" then ", Department" else if #"Level 2" = "<Product>" then ", Product" else "")])
in
Source
Now the end-user can change parameter values, by clicking Edit Queries -> Edit Parameters:
And select how to group the data:
By default, Power BI Desktop will warn you first time, when particular query is executed:
If you want to turn this off, go to File -> Options and settings -> Options -> (GLOBAL) Security and make sure Require user approval for new native database queries is not selected:
When the end-user changes parameter values, the data will change too, e.g.:
Or:
And so on...
This trick works well in Power BI Desktop when every user has its own copy of the .pbix file. However, if you publish it, first changing parameter values is not very convenient (you must go to datasat's settings) and more important, changing parameter values affects all users, which are looking at this report. You can also use it to modify Table.Group statements generated by Power Query Editor, in case you want to aggregate the data in Power BI, but changing the database query is easier and more flexible.
If you want to enable this scenario for concurrent multi-users scenarios for published reports, you can use slicers and What-if parameters. Unfortunately, What-if parameters can be numeric (you can't define the list of values there), so you can use measures to "decode" the int value of the parameter and write some DAX code to perform different aggregations accordingly. It is more work, but if it is needed, it can be made too.