CDS view with parameters and aggregate function - cds

Question

I'm doing a self-learning on CDS views and I'm having trouble with aggregate function.
Here is my code:
define view ZACT02B_MAR
as select from cosp as vp
left outer join prps as vd
on vp.objnr = vd.pspnr {
key vp.objnr as Object_No,
lednr as Ledger,
gjahr as Fiscal_Year,
wrttp as Value_Type,
versn as Version,
kstar as Cost_Element,
hrkft as CO_Key_SubNo,
coalesce( wtg001 , 0.00 ) as Total_Value,
coalesce( wtg002 , 0.00 ) as Total_Value_2
}
Now, I'm trying to apply an aggregate function which is aggregate sum of WTG and parameters GJAHR and VERSN but encountering errors.
define view ZACT03_MAR
with parameters p_gjahr : gjahr,
p_versn : versn
as select from cosp {
key gjahr,
key versn,
lednr as Ledger,
gjahr as Fiscal_Year,
wrttp as Value_Type,
versn as Version,
kstar as Cost_Element,
hrkft as CO_Key_SubNo,
coalesce( wtg001 , 0.00 ) as Total_Value,
sum( wtg001 ) as Sum_WTG001,
sum( wtg002 ) as Sum_WTG002
}
group by gjahr
//where gjahr = $parameters.p_gjahr and versn = $parameters.p_versn
Is is possible to implement parameters and aggregate at the same time? thank you

Answer 1

Using parameters and aggregations is possible in ABAP CDS.
I think you just have to change the order of the group by and the where clause. Also, in ABAP CDS, the group by statement must contain all selected fields in the cds-view except from the aggregations.
I made a simple example on the Table spfli that counts all entries depending on a parameter for the filed carrid. Note that I would get the same result with group by carrid having p_carrid = :carrid.
define view Z_Tester
with parameters p_carrid: abap.char(2)
as select from spfli
{
carrid,
count(*) as count_carrid
}
where carrid = :p_carrid
group by carrid