Invalid postback when i try a delete command

MtheK · March 11th, 2011, 10:35 AM

I am attempting to add a delete command to my data grid, and it worked fine on my previous program, but now for some reason is giving me this error message:

Quote:

Invalid postback or callback argument. Event validation is enabled using <pages enableEventValidation="true"/> in configuration or <%@ Page EnableEventValidation="true" %> in a page. For security purposes, this feature verifies that arguments to postback or callback events originate from the server control that originally rendered them. If the data is valid and expected, use the ClientScriptManager.RegisterForEventValidation method in order to register the postback or callback data for validation.

The data grid is in this format:

HTML Code:

<asp:DataGrid id=dg runat="server"  ondeletecommand="Delete_Item">  
<columns>
<asp:buttoncolumn buttontype="PushButton"   
commandname="Delete" text="Remove All" />  
</columns>  
</asp:DataGrid>

and the "Delete_Item" subroutine is here:

Code:

Sub Delete_Item(s As Object, e As DataGridCommandEventArgs)  
 
    objDT = Session("Cart")  
    objDT.Rows(e.Item.ItemIndex).Delete()  
    Session("Cart") = objDT  
 
    dg.DataSource = objDT  
    dg.DataBind()
 
End Sub

So this used to remove a row from my data grid, but not anymore.

It would be super if someone could tell me what the problem is.

jbenson001 · March 14th, 2011, 06:03 PM

It would seem that you are binding the grid elsewhere in your code. Check to make sure you don't have binding code somewhere else, such as the Page_Load event.

MtheK · March 15th, 2011, 10:57 AM

I have it call these functions on the page_load:

Code:

Private Sub Page_Load(s As Object, e As EventArgs)
	If Not IsPostBack Then
		makeCart()
	End If
		DataForGrid()

makeCart() looks like this:

Code:

Dim objDT As System.Data.DataTable 
Dim objDR As System.Data.DataRow   '<--These two lines apply for the whole script

Function makeCart()
if Session("Cart") is Nothing Then
objDT = New System.Data.DataTable("Cart") 
objDT.Columns.Add("ID", GetType(Integer)) 
objDT.Columns("ID").AutoIncrement = True 
objDT.Columns("ID").AutoIncrementSeed = 1 

objDT.Columns.Add("Quantity", GetType(Integer)) 
objDT.Columns.Add("Product", GetType(String)) 
objDT.Columns.Add("Item Cost", GetType(Decimal))
objDT.Columns.Add("Item Total", GetType(Decimal))

Session("Cart") = objDT 
End if
End Function

and DataforGrid() is in this wise:

Code:

Function DataforGrid()

	Dim objDT As System.Data.DataTable = CType(Session.Item("Cart"), System.Data.DataTable)

     dg.DataSource = objDT
     dg.DataBind()

End Function

But I can't just remove these. I need this in order to save the table when you navigate away from the data grid page. Is there some way I can have a "delete" command and still save the data grid?

jbenson001 · March 16th, 2011, 10:06 AM

put the DtaforGrid() call in the IF not page.ispostback code

MtheK · March 17th, 2011, 11:12 AM

Thanks! That worked great!

Code:

Private Sub Page_Load(s As Object, e As EventArgs)
	If Not IsPostBack Then
		DataForGrid()
		makeCart()
	End If
    
End Sub

I should be able to figure these things out, i guess, but anyways, thanks again for the help.

jbenson001 · March 17th, 2011, 01:40 PM

I'm glad I was able to help. In most cases, you will only want to load the data for your controls if it is NOT a post back.