Simple Json datasource cannot get $__timeFrom() /$__timeTo()

1

Dear all:
Need your help!
when I use :Microsoft SQL Server datasource, I can get __timeFrom()/ __timeTo()
just like:EXEC [dbo].[usp_MPScada_ProductionInfo_YieldRate] @BeginDate=’__timeFrom()',@EndDate='__timeTo()’

but when I change to Simple Json datasource , __timeFrom() /__timeTo() cannot pass to api parameter json string:{‘QueryType’:‘usp_MPScada_ProductionInfo_YieldRate’,‘BeginDate’:’__timeFrom()','EndDate':'__timeTo()’}.

Anyone can help me.
Thanks very much.