How to add Control dynamically in an ASP.NET AJAX application

Most of us know how to create controls dynamically in an ASP.NET application. However a lot of users get confused while creating controls dynamically in an ASP.NET AJAX application. This is as the there is an async postback involved. Here's a very common technique to create controls dynamically in an ASP.NET AJAX application using ViewState

<body>

    <form id="form1" runat="server">

    <div>

    <asp:ScriptManager ID="ScriptManager1" runat="server">

    </asp:ScriptManager>

    <asp:UpdatePanel ID="UpdatePanel1" runat="server">

    <ContentTemplate>

           <asp:Button ID="Button1" runat="server" Text="Create TextBoxes" onclick="Button1_Click" />

   </ContentTemplate>

   </asp:UpdatePanel>

    </div>

    </form>

</body>

    protected void Button1_Click(object sender, EventArgs e)

    {

        int cnt = 0;

        if (ViewState["txtBoxes"] != null)

            cnt = (int)ViewState["txtBoxes"];

        cnt = cnt + 1;

        ViewState["txtBoxes"] = cnt;

        for (int i = 0; i < cnt; i++)

        { 

            TextBox tb = new TextBox();

            tb.Text = ""; 

            tb.ID = "TextBox" + cnt; 

            UpdatePanel1.ContentTemplateContainer.Controls.Add(tb);

        }     

    }

VB.NET

    Protected Sub Button1_Click(ByVal sender As Object, ByVal e As EventArgs)

        Dim cnt As Integer = 0

        If ViewState("txtBoxes") IsNot Nothing Then

            cnt = CInt(Fix(ViewState("txtBoxes")))

        End If

        cnt = cnt + 1

        ViewState("txtBoxes") = cnt

        For i As Integer = 0 To cnt - 1

            Dim tb As New TextBox()

            tb.Text = ""

            tb.ID = "TextBox" & cnt

            UpdatePanel1.ContentTemplateContainer.Controls.Add(tb)

        Next i

    End Sub

About The Author

Suprotim Agarwal, Developer Technologies MVP (Microsoft Most Valuable Professional) is the founder and contributor for DevCurry, DotNetCurry and SQLServerCurry. He is the Chief Editor of a Developer Magazine called DNC Magazine. He has also authored two Books - 51 Recipes using jQuery with ASP.NET Controls. and The Absolutely Awesome jQuery CookBook.

Follow him on twitter @suprotimagarwal.

How to add Control dynamically in an ASP.NET AJAX application

About The Author

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