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POASP.NET dynamic controls count (creating controls as you go)
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  1. POASP.NET dynamic controls count (creating controls as you go)
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    copied!<p>I'm trying to create a composite ASP.NET control that let's you build an editable control collection.</p> <p>My problem is that when I press the add or postback button (which does nothing other than to postback the form) any values entered in the text boxes are lost.</p> <p>I can't get it to work when the number of controls change between postbacks. I need to basically be able to recreate the control tree at two different times in the control life-cycle depending on the view state property <code>ControlCount</code>.</p> <p>This test can be used to reproduce the issue:</p> <pre><code>public class AddManyControl : CompositeControl { protected override void OnLoad(EventArgs e) { base.OnLoad(e); EnsureChildControls(); } protected override void CreateChildControls() { var count = ViewState["ControlCount"] as int? ?? 0; for (int i = 0; i &lt; count; i++) { var div = new HtmlGenericControl("div"); var textBox = new TextBox(); textBox.ID = "tb" + i; div.Controls.Add(textBox); Controls.Add(div); } ViewState["ControlCount"] = count; var btnAdd = new Button(); btnAdd.ID = "Add"; btnAdd.Text = "Add text box"; btnAdd.Click += new EventHandler(btnAdd_Click); Controls.Add(btnAdd); var btnPostBack = new Button(); btnPostBack.ID = "PostBack"; btnPostBack.Text = "Do PostBack"; Controls.Add(btnPostBack); } void btnAdd_Click(object sender, EventArgs e) { ViewState["ControlCount"] = (int)ViewState["ControlCount"] + 1; } protected override void OnPreRender(EventArgs e) { base.OnPreRender(e); // If I remove this RecreateChildControls call // the collection lags behind each postback // because the count is incremented in the btnAdd_Click event handler // however, the values are not lost between postbacks RecreateChildControls(); } } </code></pre>
 

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