cascading dropdown problem

Question

1.00/5 (1 vote)

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Hi,
I have a cascading dropdownlists. When you select an item from the first ddl, the 2nd ddl gets populated with the correct list. The problem is when you select an item from the 2nd ddl, it always shows the first item on the list and it does not populate the 3rd ddl. How can I solve this without ajaxtoolkit?

UPDATE by OP:
here is the code

XML

<form id="Form1" method="post" runat="server">
  <asp:ScriptManager ID="ScriptManager" runat="server" />
    <asp:UpdatePanel ID="Panel1" runat="server" ChildrenAsTriggers="true">
    <ContentTemplate>
        <asp:DropDownList ID="cbCL" runat="server" Width="209px" AutoPostBack="true" OnSelectedIndexChanged="SetShip" ></asp:DropDownList>
        <asp:DropDownList ID="cbShip" runat="server" Width="209px" AutoPostBack="true" OnSelectedIndexChanged="SetPort" ></asp:DropDownList>
        <asp:DropDownList ID="cbPort" runat="server" Width="209px" AutoPostBack="true" ></asp:DropDownList>
        <asp:DropDownList ID="cbMerchant" runat="server" Width="209px" ></asp:DropDownList>
    </ContentTemplate>
    </asp:UpdatePanel>
</form>

SQL

Public Sub SetShip(ByVal sender As Object, ByVal e As System.EventArgs)
         Common.BindShipByCL(cbShip, cbCL.SelectedItem.Value, Date.Today)
  End Sub
  Public Sub SetPort(ByVal sender As Object, ByVal e As System.EventArgs)
     Common.BindPortByShip(cbPort, cbShip.SelectedItem.Value, Date.Today)   
  End Sub

Thanks,
Martin

Posted 14-Sep-10 9:53am

Martin_

Updated 15-Sep-10 8:32am

Sandeep Mewara

v2

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Comments

AspDotNetDev 14-Sep-10 16:56pm

Show us what code you are using. It's obvious your code is wrong, so seeing it would help us help you to fix it.

4 solutions

Solution 5

If you see the code, you will find that the cascading dropdowns are present in a single update panel and thus all will get refreshed based on postback of any one.

Surely, before picking up the second dropdown value for populating 3rd one is lost and thus nothing happens.
Just use DEBUGGER and that should tell you how the execution is happening. Further, if you have missed using Page.IsPostback & ScriptManager.IsInAsyncPostBack page properties then do apply them such that the dropdowns are not getting freshly populated before the onchange event is fired.

Posted 15-Sep-10 8:31am

Sandeep Mewara

Solution 6

I am using Page.IsPostback to load the first ddl. But I am not using IsInAsynchPostBack. I've never used it, I'm not sure how to use it.

VB

Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
    If (Not Page.IsPostBack) Then
        Common.BindCruiseLine(cbCL)
    End If
End Sub

Posted 15-Sep-10 9:34am

Martin_

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Sandeep Mewara · Accepted Answer · 2010-09-15T07:27:00

Solution 3

There are various ways to get Cascading dropdown. Earlier it was Server side, then traditional AJAX==XMLHttpRequest. Now, we can use Update panel or PageMethod for it.

Ajaxtoolkit provide a cascading control. One can opt not to use it and have any one of the above.

Surely the selections should work. Use XMLHttpRequest or UpdatePanel or PageMethod.

Posted 15-Sep-10 7:27am

Sandeep Mewara

Comments

Martin_ 15-Sep-10 14:17pm

Reason for my vote of 5
Automatic vote of 5 for accepting answer.

Dalek Dave 15-Sep-10 15:53pm

Good Answer

Ashika s · Accepted Answer · 2010-09-14T19:01:00

Solution 1

Hi,
If u using cascading dropdown list, U must using ajax tool kit.

Posted 14-Sep-10 19:01pm

Ashika s

Comments

Sandeep Mewara 15-Sep-10 2:37am

Not necessarily!

There are various ways to get Cascading dropdown. Earlier it was Server side, then traditional AJAX==XMLHttpRequest. Now, we can use Update panel or PageMethod for it.

Ajaxtoolkit provide a cascading control. One can opt not to use it and have any one of the above.

Martin_ 15-Sep-10 11:21am

Reason for my vote of 5
Automatic vote of 5 for accepting answer.

Sergey Alexandrovich Kryukov 14-Aug-11 2:24am

That brings the question: why would you accept this wrong answer?
--SA

William Winner 15-Sep-10 13:34pm

Reason for my vote of 1
as has been said, there are many ways to do it without the ajax toolkit.

Manfred Rudolf Bihy 12-Aug-11 11:12am

No text speak please! Read the FAQ!