session and gridview RSS

• • Reply
  

  anguswong

  Member

  13 Points

  30 Posts

  session and gridview

  Nov 24, 2009 01:17 AM|LINK

  hi guys, i got a problem with the following script. though it serves exactly the functions i want, i don't quite understand the mechanism.

  my question is:"when did the session("cart") get updated? i don't see statement like---session("cart")="datatable object" in the script, but the session actually get updated after running the codes!!!

  
  

  following is the script which i wrote and tested.

  =====================================
  

  the functionality is perfect, coz i just followed an example in msdn library:" http://msdn.microsoft.com/zh-tw/library/system.web.ui.webcontrols.gridview.rowupdating.aspx ”
  

  
  <script runat="server" language="vb">
  dim objdt as datatable
  dim objdr as datarow
  
  protected sub page_load(byval sender as object, byval e as system.eventargs) handles me.load
  
  If Not Page.IsPostBack Then
  objdt=session("cart")
  
  gv.DataSource = objDT
  gv.DataBind()
  end if
  
   response.Write(gv.rows(0).cells(2).text)
  
  
  
  
  end sub
  
  Sub Delete_Item(s As Object, e As DataGridCommandEventArgs)
       objdt = Session("Cart")
       objdt.Rows(e.Item.ItemIndex).Delete()
       Session("Cart") = objDT
  
       gv.DataSource = objDT
       gv.DataBind()
      
      
      
  end sub
  
  Protected Sub rowediting(ByVal sender As Object, ByVal e As GridViewEditEventArgs)
     
      gv.EditIndex = e.NewEditIndex
  
      binddata()
    End Sub
  
    Protected Sub cancelingedit(ByVal sender As Object, ByVal e As GridViewCancelEditEventArgs)
   
      gv.EditIndex = -1
  
      binddata()
    End Sub
  
    Protected Sub Updating(ByVal sender As Object, ByVal e As GridViewUpdateEventArgs)
   
      
      objdt=session("cart")
  
      Dim row As GridViewRow = gv.Rows(e.RowIndex)
      objdt.Rows(gv.EditIndex)("quantity") = (CType((row.Cells(2).Controls(0)), TextBox)).Text
   
   
     
      gv.EditIndex = -1
  
  
       bindData()
     
      
    End Sub
    Private Sub BindData()
      gv.DataSource = session("cart")
      gv.DataBind()
    End Sub
  
  
  
  
  
  </script>
  

  ASP.NET2.0 data binding please help..

• • Reply
  

  Danish Ali

  Contributor

  3384 Points

  468 Posts

  Re: session and gridview

  Nov 24, 2009 01:23 AM|LINK

  Here it is getting update.

  Sub Delete_Item(s As Object, e As DataGridCommandEventArgs)
       objdt = Session("Cart")
       objdt.Rows(e.Item.ItemIndex).Delete()

  
       Session("Cart") = objDT
  
       gv.DataSource = objDT
       gv.DataBind()
       
      
       
  end sub

  If my post solves your problem, please mark it as an answer.
• • Reply
  

  anguswong

  Member

  13 Points

  30 Posts

  Re: session and gridview

  Nov 24, 2009 01:43 AM|LINK

  thanks for ur reply.

  but actually "sub delete_item()" didn't get involved in the whole process coz i had not use that part yet. i was only

  using the editing function~
  

• • Reply
  

  Danish Ali

  Contributor

  3384 Points

  468 Posts

  Re: session and gridview

  Nov 24, 2009 02:02 AM|LINK

  Ok. I got it. Wht's happing is that you have a global variable of DataTable Type.

  dim objdt as datatable

  
  

  Now when you write this statement.

  objdt=session("cart")

  it set the memory reference of datatable object in objdt variable from session. And now objdt is pointing to same memory location, to which session("cart") is pointing.

  
  

  So now when in the below "Updating" function, you update "objdt"  datatable. it updates the object of same memory location, to which session("cart") is pointing. That's why your session variable get updated.

  
  

  Protected Sub Updating(ByVal sender As Object, ByVal e As GridViewUpdateEventArgs)
   
      objdt=session("cart")
  
      Dim row As GridViewRow = gv.Rows(e.RowIndex)
      objdt.Rows(gv.EditIndex)("quantity") = (CType((row.Cells(2).Controls(0)), TextBox)).Text
   
      
      gv.EditIndex = -1
  
  
       bindData()
     
      
    End Sub

  
  

  Hope it will help.

  If my post solves your problem, please mark it as an answer.
  • Marked as answer by anguswong on Nov 24, 2009 03:20 AM
• • Reply
  

  anguswong

  Member

  13 Points

  30 Posts

  Re: session and gridview

  Nov 24, 2009 03:19 AM|LINK

  i don't know what exactly is happening inside the machines, but it makes sense. thanks a lot dude~~