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POASP.NET Webforms cascading dropdown Lists - second list's selected value resets on postback
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  1. POASP.NET Webforms cascading dropdown Lists - second list's selected value resets on postback
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    copied!<p>My problem's probably trivial, but I can't remind myself how to do that. I have 2 dropdown lists:</p> <pre><code>&lt;span&gt; &lt;asp:DropDownList ID="DDLEditWydzial" runat="server" DataSourceID="SqlListaWydzialow" AutoPostBack="true" DataTextField="NazwaWydzialu" DataValueField="ident" OnSelectedIndexChanged="OnWydzialChanged" EnableViewState="true"&gt; &lt;/asp:DropDownList&gt; &lt;/span&gt; &lt;span&gt; &lt;span style="font-size: 8pt; font-family: Arial CE"&gt; &lt;asp:DropDownList ID="DDLEditSale" runat="server" EnableViewState="true" AutoPostBack="true"&gt; &lt;/asp:DropDownList&gt; &lt;/span&gt; &lt;/span&gt; </code></pre> <p>First one is filled with via <code>SqlDataSource</code>, second is filled depending on choice in previous. This is done by an event handler:</p> <pre><code>protected void OnWydzialChanged(object sender, EventArgs e) { SqlConnection conn = new SqlConnection(ConfigurationManager.ConnectionStrings["sworConnectionString"].ConnectionString); conn.Open(); using (conn) { SqlCommand command = new SqlCommand("SELECT '-- wybierz salę --' as numer, -1 as ident UNION " + "SELECT 'Sala ' + s.numer as numer, s.ident FROM sala s, sala_wydzial sw where s.czyus=0 and sw.id_wydzial=" + DDLEditWydzial.SelectedValue + " and sw.id_sala = s.ident", conn); SqlDataReader salaReader = command.ExecuteReader(); DDLEditSale.AppendDataBoundItems = true; DDLEditSale.DataSource = salaReader; DDLEditSale.DataTextField = "numer"; DDLEditSale.DataValueField = "ident"; DDLEditSale.DataBind(); conn.Close(); conn.Dispose(); } } </code></pre> <p>Then, when I chose value from 2nd list, comes postback and after a refresh list contains with data, but nothing in 2nd DDL is selected. I've checked Page_Load and DDLEditSale is empty then.</p> <p>Any ideas?:)</p> <p>EDIT: OnInit and InitializeComponent code (it's generated by ZedGraph):</p> <pre><code>override protected void OnInit(EventArgs e) { // // CODEGEN: This call is required by the ASP.NET Web Form Designer. // InitializeComponent(); base.OnInit(e); } /// &lt;summary&gt; /// Required method for Designer support - do not modify /// the contents of this method with the code editor. /// &lt;/summary&gt; private void InitializeComponent() { this.ZedGraphWeb1.RenderGraph += new ZedGraph.Web.ZedGraphWebControlEventHandler(this.OnRenderGraph); } </code></pre>
 

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