Asp.net DropDownList, AutoPostBack, and ViewState

[Corey]

I'm trying to finish off do an ASP.NET project where a DropDownList box is
used to access a Table.
Once you Make a selection on an item in the DropDownListBox, it updates a
DataView, and text boxes on the form get updated.

I'd like to do this without a submit button.

Shouldn't the DropDownList box PostBack?
Why does SelectedIndexChanged never get hit?
Does the answer lie within ViewState?

Any Info will help...

Thanks.

 

[Cor Ligthert]

Corey,

Only the button has his autopostback standard set too true. For the other
controls you have to set that in the properties.

I hope this helps,

Cor

 

[Corey]

Thanks Cor.

I made the change to the text boxes. Unfortunately there's no change,
except now when I type in them i get an Javascript Error In Internet
Explorer which says

Error: Object expected

I think I know what is causing this. It's a parameter for a dataset, which
is missing.

But what i noticed with the DropDownList is when I changed it, I get a
javascript error for it too.
It says

Line: 1
Char: 1
Error: 'WebForm_PostBackOptions' is undefined
Code: 0

Does This Help at all? I've searched google and came up with very little.

Thanks.

 

[Cor Ligthert]

Corey,

I made the change to the text boxes.

You said dropdownlist, that is the only place you should set the
autopostback to true in my opinion.

Cor

 

[Corey]

Yeah, I removed it from the text boxes before.

Any clues on my Javascript error?

 

[Cor Ligthert]

Corey,

Can you show by a little piece how you did your code, it is ASPNET and for
that are three possibilities.

Cor

 

[Corey]

Here's My Code

<form id="Form1" method="post" runat="server">

<asp:textbox id=txtFirstName style="Z-INDEX: 101; LEFT: 33px; POSITION:
absolute; TOP: 56px" runat="server" Width="235px" Height="23px" Text='<%#
DataBinder.Eval(dvUsers1, "[0].FirstName", "{0}") %>'>

</asp:textbox><asp:textbox id=txtLastName style="Z-INDEX: 102; LEFT:
34px; POSITION: absolute; TOP: 99px" runat="server" Width="235px"
Height="24px" Text='<%# DataBinder.Eval(dvUsers1, "[0].LastName", "{0}")
%>'></asp:textbox><asp:datagrid id=DataGrid1 style="Z-INDEX: 103; LEFT:
323px; POSITION: absolute; TOP: -48px" runat="server" Width="386px"
Height="137px" Visible="False" DataMember="Users" DataKeyField="UserKey"
DataSource='<%# DataBinder.Eval(DsUsers1, "Tables[Users]") %>'>

</asp:datagrid><asp:dropdownlist id=DropDownList1 style="Z-INDEX: 104;
LEFT: 36px; POSITION: absolute; TOP: 20px" runat="server" Width="227px"
Height="27px" DataMember="Users" DataSource="<%# DsUsers1 %>"
DataValueField="UserKey" EnableViewState="True" AutoPostBack="True"
DataTextField="UserID">

</asp:dropdownlist><asp:datagrid id=DataGrid2 style="Z-INDEX: 105; LEFT:
34px; POSITION: absolute; TOP: 135px" runat="server"
DataMember="sp_RulesLookup" DataKeyField="ruledescr" DataSource="<%#
DsRulesLookup1 %>" AutoGenerateColumns="False">
<Columns>
<asp:BoundColumn DataField="ruledescr" SortExpression="ruledescr"
HeaderText="Rules"></asp:BoundColumn>
</Columns>
</asp:datagrid><asp:button id="Button1" style="Z-INDEX: 106; LEFT: 321px;
POSITION: absolute; TOP: 99px" runat="server" Width="250px" Height="28px"
Text="Save Changes"></asp:button><asp:button id="Button2" style="Z-INDEX:
107; LEFT: 324px; POSITION: absolute; TOP: 141px" runat="server"
Width="253px" Height="28px" Text="Button"></asp:button></form>

 

[Cor Ligthert]

Corey,

This is the mainly RAD created part of your code.
I don't know if you have any VBcode so called code behind.

The problem with this is that I cannot simulate what you did, because it
depends on your evironment that you draged on your form.

However there must be as well a part wherin is that event from the
dropdownlist.

Cor

 

[Alvin Bruney [ASP.NET MVP]]

Why is the Xposted all over the place?

--
Regards,
Alvin Bruney
[Shameless Author Plug]
The Microsoft Office Web Components Black Book with .NET
available at www.lulu.com/owc
_________________________

 

[Corey]

Any time i try to change the DropDownList I get a javascript error which
says "Error: 'WebForm_PostBackOptions' is undefined"
How can I restore this?

VB Code is as follows.


Private Sub Page_Load(ByVal sender As System.Object, ByVal e As
System.EventArgs) Handles MyBase.Load

'Put user code to initialize the page here

If Not IsPostBack Then

SqlDAUsers.Fill(DsUsers1)

DropDownList1.DataBind()

' DataGrid1.DataBind()

' dvUsers1.RowFilter = "Userkey = " & Me.ViewState("DropDownList1") '&
DsUsers1.Users.UserKeyColumn.ToString()

txtFirstName.DataBind()

txtLastName.DataBind()

SqlDARulesLookup.SelectCommand.Parameters.Item(1).Value =
DropDownList1.SelectedItem.Value

SqlDARulesLookup.Fill(DsRulesLookup1)

DataGrid2.DataBind()

End If

' Response.Write("Selected - " + DropDownList1.SelectedItem.Value)

' Response.Write("Uber Select - " & DropDownList1.SelectedIndex)

End Sub

Private Sub DropDownList1_SelectedIndexChanged(ByVal sender As
System.Object, ByVal e As System.EventArgs) Handles
DropDownList1.SelectedIndexChanged



' txtFirstName.Text = DsUsers1.Users.FirstNameColumn.ToString

' txtLastName.Text = DsUsers1.Users.LastNameColumn.ToString

dvUsers1.RowFilter = "Userkey = " & DsUsers1.Users.UserKeyColumn.ToString()

txtFirstName.DataBind()

txtLastName.DataBind()

Response.Write("SelectedIndex!")

End Sub

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As
System.EventArgs) Handles Button1.Click

Dim strSQLQuery As String

strSQLQuery = "UPDATE Users " _

& "SET FirstName = '" & Replace(txtFirstName.Text, "'", "''") & "', " _

& "LastName = '" & Replace(txtLastName.Text, "'", "''") & "' " _

& "WHERE UserKey = " & DropDownList1.SelectedItem.Value & ";"

'Response.Write(strSQLQuery)

SqlSaveCommand.CommandText = strSQLQuery

SqlUsers.Open()

SqlSaveCommand.ExecuteNonQuery()

SqlUsers.Close()

'update datasets?

End Sub

Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As
System.EventArgs) Handles Button2.Click

' Define Crystal Reports variables

Dim crReportDocument As ReportDocument

Dim crExportOptions As ExportOptions

Dim crDiskFileDestinationOptions As DiskFileDestinationOptions

Dim Fname As String

' The following code can be placed directly after the call to

' InitializeComponent() in the form's constructor, or inside of

' a Button_Click event where the button is used by the client to

' get a printable copy of the report.

crReportDocument = New ReportDocument()

' The following line of code loads the sample report "Chart.rpt" that
installs

' with Visual Studio .NET

crReportDocument.Load("C:\Inetpub\wwwroot\WebApplication3\CrystalReport2.rpt")

Fname = "C:\inetpub\wwwroot\WebApplication3\" & Session.SessionID.ToString &
".pdf"

crDiskFileDestinationOptions = New DiskFileDestinationOptions()

crDiskFileDestinationOptions.DiskFileName = Fname

crExportOptions = crReportDocument.ExportOptions

With crExportOptions

..DestinationOptions = crDiskFileDestinationOptions

..ExportDestinationType = ExportDestinationType.DiskFile

..ExportFormatType = ExportFormatType.PortableDocFormat

End With

crReportDocument.Refresh()

crReportDocument.Export()

' The following code writes the pdf file to the Client's browser.

Response.ClearContent()

Response.ClearHeaders()

Response.ContentType = "application/pdf"

Response.WriteFile(Fname)

Response.Flush()

Response.Close()

'delete the exported file from disk

System.IO.File.Delete(Fname)

End Sub

End Class

 

[Corey]

Visual Studio must have put them in.

Why is the Xposted all over the place?

--
Regards,
Alvin Bruney
[Shameless Author Plug]
The Microsoft Office Web Components Black Book with .NET
available at www.lulu.com/owc
_________________________

I'm trying to finish off do an ASP.NET project where a DropDownList box
is used to access a Table.
Once you Make a selection on an item in the DropDownListBox, it updates a
DataView, and text boxes on the form get updated.

I'd like to do this without a submit button.

Shouldn't the DropDownList box PostBack?
Why does SelectedIndexChanged never get hit?
Does the answer lie within ViewState?

Any Info will help...

Thanks.

 

[Cor Ligthert]

Answered in the follow up thread