ASP.NET Page events calling twice

Question

I have code in one of my pages which is as given below:

<asp:button id="btnTest" runat="server" onclick="btnTest_click" />
<div class="TomasForm">
        <ul>
            <li>
                <asp:Label ID="LineL" runat="server" AssociatedControlID="Lines" Text="<%$ FieldLabelResources:Units, Line, false %>" />
                <asp:DropDownList ID="Lines" runat="server" AutoPostBack="true" AppendDataBoundItems="true"
                    DataTextField="Name" DataValueField="Id" OnSelectedIndexChanged="Lines_SelectedIndexChanged">
                    <asp:ListItem Text="<%$ Resources:Common, SelectOne %>" Value="-1" />
                </asp:DropDownList >
            </li>
        </ul>
    </div>

My issue is when I change the Lines dropdownlist value, the page(page_load and Lines_SelectedIndexChanged events) is getting called twice. The page is behaving normal when I click btnTest button.

Could anyone let me know why this is happening??

Thanks, Mahesh

You might want to paste the code from your SelectedIndexChanged event handler. — Graham Clark
– Graham Clark, Commented May 19, 2011 at 10:51
If you set the selected value in your page load eventhandler(or other life cycle event) then you will cause the changed event to fire again. — Chad
– Chad, Commented May 19, 2011 at 13:08

Steve Kiss · Accepted Answer · 2011-05-19 10:41:39Z

1

You need to change the AutoPostBack to False in your DropDownList.

answered May 19, 2011 at 10:41

Steve Kiss

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1 Comment

Graham Clark Over a year ago

but if the OP wants the page to postback when the dropdownlist is changed (which is fine), it shouldn't be firing the page events twice...

AjayR · Accepted Answer · 2011-05-19 10:49:32Z

0

You should set the AutoPostback to false for dropdown list and in code,make sure you write the condition like this in Page_Load if (!isPostBack()) { // Write your code, it will work only once }

answered May 19, 2011 at 10:49

AjayR

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2 Comments

Mahesh Over a year ago

But, I want to postback when the dropdown value is changed.

Mahesh Over a year ago

This is the postback code I am using: protected void Page_Load(object sender, EventArgs e) { if (!IsPostBack) { Lines.DataSource = TomasContext.Current.GetTubeLines(); Lines.DataBind(); } }

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