Selected Date Period

[Slindheim]

My Problem is as follows:

I have a table where I want to show sales. It should be possible to show the sales by picking a specific year or by picking a time period. Furthermore there should be the possibility to select a certain customer. And there is the main problem: a specific customer is not buying products everyday. For example:
Customer A buys goods on the 5th and on the 12th of September 2020.
If I pick the daterange of the 1st to 30th September of 2020, Qlik only shows the range from the 5th to the 12th. Because - obviously - the customer only bought goods on these two days. Then the header of the column is 'Sales from the 05.09.2020 to the 12.09.2020'.

(Variables are vDateMin=min(Calendar.Date) and vDateMax=max(Calendar.Date))

My intention is that the header shows the selected time period -> 'Sales from the 01.09.2020 to the 30.09.2020'

So, in the background Qlik selects only the days where sales have taken place, but on the surface one should see the originally selected time period.

Is there a way to solve my problem via Variables?
I tried several options of getselectedcount or other getselected field functions. But none of them worked.

I hope anyone can help me.

[GaryGiles · Accepted solution]

If I understand your question correctly, I think you need to use the 1 identifier to ignore all selection and then include Calendar.Date in the set analysis to apply any selections made on Calendar.Date (or whatever date field you are using in your filter.

vDateMin = min({1<Calendar.Date=$::Calendar.Date>} Calendar.Date)

vDateMax = max({1<Calendar.Date=$::Calendar.Date>} Calendar.Date)