ASP.Net DropDownList OnSelectedIndexChange not firing

Question

I have the following DropDownList control:

<asp:label runat="server" text="Filter by state: "></asp:label>
<asp:dropdownlist runat="server" id="filterbystate" 
    OnSelectedIndexChanged="FilterByState">
    <asp:ListItem value="all" selected="True">All</asp:ListItem>
    <asp:ListItem value="ca" selected="False">California</asp:ListItem>
    <asp:ListItem value="co" selected="False">Colorado</asp:ListItem>
    <asp:ListItem value="id" selected="False">Idaho</asp:ListItem>
    <asp:ListItem value="ut" selected="False">Utah</asp:ListItem>
</asp:dropdownlist>

Here is the method:

protected void FilterByState(object sender, EventArgs e)
{
    var value = e;
}

The method will not fire for some reason. I select a different value and nothing happens. What I am trying to do is reload the page passing in the state value so I can filter the results by it.

What am I doing wrong?

Answer 1

Set AutoPostBack=True as an attribute of your DDL and it will automatically post back the selected index change event

Answer 2

Add this to dropdown list aspx it will cause a request to be send to the server and your event will be fired.

AutoPostBack="true"