在会话中存储ArrayList值

Question

I have a particular problem regarding the and an ArrayList: " ".

I have stored certain values in Session["arr3"] , and upon the click event of a button eg ' ', I want to assign the Session["arr3"] the following values:-


But I am recieving the following compilation error:-
Operator '+' cannot be applied to operands of type 'object' and 'System.Collections.ArrayList'

Or I may make it simple as:-

This is causing the following compilation error:-
"Operator '+=' cannot be applied to operands of type 'object' and 'System.Collections.ArrayList'".

: The objective to do this is to hold the Session["arr3"]'s values (this is what I am referring to old value of Session["arr3"] ), and then add the ArrayList arr3's values to the Session["arr3"], and then these two combined values ( Session["arr3"] + arr3) are then stored in the Session["arr3"]. Now this will be the new Session["arr3"]'s value. This value will be saved/inserted in a DB Table.

I want to retain the old value of Session["arr3"], and add the old value with the arr3(ArrayList) value and save in the Session["arr3"]. And this final Session["arr3"] value is inserted in a Database's Table.

Please help me in this aspect at earliest.

Answer 1

If I understand correctly, you have an existing ArrayList in session. You also have a new ArrayList called arr3 and you want to join them together, storing the result back in the session.

If so, you need to cast your session object back to what it is before appending the new elements:

Session["arr3"] = ((ArrayList)Session["arr3"]).AddRange(arr3);

This will take the original ArrayList from the session, append the elements in arr3, and put it back in the session.