asp.net - Dynamically adding multiple rows to a ASP Datagrid -

i have page 2 datagrids. 1 reads value database , allows selection. when user selects grid adds data second datagrid. code using this:

    protected sub page_load(byval sender object, byval e system.eventargs) handles me.load      dim dc1 new datacolumn("name")     dim dc2 new datacolumn("price")     dt.columns.add(dc1)     dt.columns.add(dc2)     dim dr1 datarow = dt.newrow()     gridview2.datasource = dt     gridview2.databind() end sub 

and

protected sub gridview1_selectedindexchanged(sender object, e eventargs) handles gridview1.selectedindexchanged         dim dr1 datarow = dt.newrow()          dr1(0) = name.tostring         dr1(1) = price.tostring         dt.rows.add(dr1)         gridview2.datasource = dt         gridview2.databind() 

now, works perfectly.... work under forms service. in web based enviroment whenever user selects value in grid 1 resets values in grid 2 , need multiple rows added 2nd datagrid every time user selects value. "data adding" fired when selectedindexchanged event takes place in gridview1. think need save data session/cookie have no idea how in case of datagrid. like, should save , how i'd read it. both gridviews under update panel control postback should instantaneous (if needed).

sightly updated code...

protected sub page_load(byval sender object, byval e system.eventargs) handles me.load     if not ispostback         dt = directcast(session("purchase"), datatable)     else         dim dc1 new datacolumn("name")         dim dc2 new datacolumn("price")         dt.columns.add(dc1)         dt.columns.add(dc2)         dim dr1 datarow = dt.newrow()         gridview2.datasource = dt         gridview2.databind()     end if end sub 

and

            dim dr1 datarow = dt.newrow()         session.add("purchase", dt)         dr1(0) = name.tostring         dr1(1) = price.tostring         dt.rows.add(dr1)         dt = directcast(session("purchase"), datatable)         gridview2.datasource = dt         gridview2.databind() 

try this:

protected sub page_load(byval sender object, byval e system.eventargs) handles me.load     'this load dt session when page loads , skip on subsequent page loads.     if not ispostback         dim dc1 new datacolumn("name")         dim dc2 new datacolumn("price")         dt.columns.add(dc1)         dt.columns.add(dc2)         session.add("purchase", dt)         gridview2.datasource = dt         gridview2.databind()     end if end sub 

gridview1_selectedindexchanged:

'clear out old datasource. gridview2.datasource = nothing gridview2.databind() 'pull datatable session variable dt = directcast(session("purchase"), datatable) 'create new row , set values dim dr1 datarow = dt.newrow() dr1(0) = name.tostring dr1(1) = price.tostring 'add row table dt.rows.add(dr1) 'if session variable exists(which should) overwrite it, if not create it. if session("purchase") nothing session.add("purchase", dt) else session("purchase") = dt 'reset datasource of datagrid gridview2.datasource = dt gridview2.databind() 

one thing i've run doing before in order datasource update expected needed gridview2.datasource = nothing , gridview2.databind() first thing in event handler, i'm not sure why works when , doesn't when don't didn't spend time looking it.