protected void lstListView_DataBound(object sender, EventArgs e)

        {

            if (lstListView.Controls[0].FindControl("lblInsertHeader").IsNotNull() &&

lstListView.Items.Count == 0)

            {

                ((Label)lstListView.Controls[0].FindControl("lblInsertHeader")).Text = this.Header;

            }

        }

Source: http://stackoverflow.com/questions/70758/does-anyone-know-of-a-way-of-hiding-a-column-in-an-asp-net-listview

If we need to get all the selected keys for each ListViewDataItem based on a selected checkbox, this is how its done:

 <asp:ListView ID="lstDocuments" runat="server" DataKeyNames="templateid">

  .....

</

public IList<string> GetSelectedTemplates()

{

     IList<string> selectedTemplates = new List<string>();

     foreach (ListViewDataItem item in lstDocuments.Items)

        {

            if (item.ItemType == ListViewItemType.DataItem)

            {

               CheckBox checkbox = (CheckBox)item.FindControl("chkSelect");

               if (checkbox.Checked)

               {

               selectedTemplates.Add((string)lstDocuments.DataKeys[item.DataItemIndex].Value);

               }

            }

        }

    return selectedTemplates;

}

 <%# Eval("StartDate", "{0:dd/MM/yyyy}")%>

public System.Drawing.Image Base64ToImage(string base64String)

        {

            // Convert Base64 String to byte[]

            byte[] imageBytes = Convert.FromBase64String(base64String);

            MemoryStream ms = new MemoryStream(imageBytes, 0,

              imageBytes.Length);

            // Convert byte[] to Image

            ms.Write(imageBytes, 0, imageBytes.Length);

            System.Drawing.Image image = System.Drawing.Image.FromStream(ms, true);

            image.Save(@"C:\Projects\Base64Image\MyImage2.jpg");

            return image;

        }

Example Images:

string img = @"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";

string img2 = @"/9j/4AAQSkZJRgABAQAAAQABAAD/2wBDAAgGBgcGBQgHBwcJCQgKDBQNDAsLDBkSEw8UHRofHh0aHBwgJC4nICIsIxwcKDcpLDAxNDQ0Hyc5PTgyPC4zNDL/2wBDAQkJCQwLDBgNDRgyIRwhMjIyMjIyMjIyMjIyMjIyMjIyMjIyMjIyMjIyMjIyMjIyMjIyMjIyMjIyMjIyMjIyMjL/wAARCABQAFADASIAAhEBAxEB/8QAGwAAAgMBAQEAAAAAAAAAAAAABAcDBQYBAgD/xAA2EAACAQIEBQIEAwcFAAAAAAABAgMEEQAFEiEGEzFBUSJhFHGRoSMygQcVQlJiscEkM4Ki0f/EABgBAAMBAQAAAAAAAAAAAAAAAAIDBAEA/8QAIhEAAgIBBAMAAwAAAAAAAAAAAAECESEDEjFBBBMyFXHh/9oADAMBAAIRAxEAPwDfBMfcvE5AUEkgAdSTjoW4uDcHvizcRUQcu2OhfbEpQ486cbuMo4FGJVjBxxFwTHGQQSNsC5hKFk9NEqJqbck9D4wV8VGrEbWt2GKTiGpr6bJKmTKo0lryFWFWt1LAE2YgGy3IHe2PHD2aSZpkNNW1SpBNLqOkjSbBiBcECx2wlyt0UKNRtF6lZIQUa5B6YDlZ9XS++OCphDC8qXP9Q3wFW5vR0gYvMrMP4E3Jxpgpcy4szWk4VqKSR450dOXzZXJeME9b23t74D4B41cZ3T0k9S0NNICZgxJjUAbWvcg3IF/bA2a5Hyssd6mrmiiRdIIpg97m25BJtvbYH74KyKlymmyyIPl81PIpbmzs5GskLuoKXC+1u3fESbxJ8jtvQ6Ekimj5kciOn8ysCPqMc1x2J1rYdd8LJFELSGPN6OBZAG2nK9R3t3t3x8OJ62iqEpWWCvXRs0Gq5Pa7HYnpfD/dX0qFevtDHaupozbUWP8ASL442c/wxwC3lzvhYScaVUkqSQ0nKgjVjKpGsk9t7bW/xiKj4qrqlRKyFgVtpJsOhJwMvIjaVHKNDEzYVNZSTOTGoMStC17BWBN7nt23xVJVZjleWxSZxaWGSITxz0zB5IkK30urW23sD07XG15ZM/WmyRmMZlWKIylVYEuugEgbb7XPUbeb4wnFmaVMddUUkj3hW7oo/LpIuPnttvfxh83SBgreRhZbNlGeIjDMMxjDj1Ry0nKKN3U3NiR7X6Yo+NcifL8lnrsrrPjKeMq0inaSMXtcjoRfvYYxzVdQVTXPLfSAfUewF8T0/EdfRMrCfWu5ZZRqBB6g+x3xO5WqZRsXQRNkLVGVpyKcSTCGRUULv+ZyFt1vuMQ0/D+ZwCniSjmFNotM6wM2lrb6bA+/g41eUZpU/u6Wnlkply4x8mJpZB+KbWsLEtY377+2BaaqpMo5qQxyqzhkqIoHbloP+V9RPTY9SLgjbCXrS5WAo6RnqmgeBZpBJMGjU2ApzHuOx/TA9Bm9VJ/p1oo202jWeNSzBySq3+1/a+GTkw+PhkWSNoYVVeRdQAFt09Nv89OvbBtZDkmW0srvTKo0HW4Qs9rb2PX6Y6MpS+sm1t4wKXNOIs74bzCLIqaCllRyDHJErHnM9t4zpuN9O1jvbbpjkuU0qZS9aPjaargUvMnMDa2udQ2A0hbWPW+objoYIeIaxaCmoGjqJ1oi6wzTRya9JN16EW8Gx6eOpIevpY+GZ6N4qn42chmqKiOwCMwYqGJ3IFjvbf5YakBhsusmCR8JVkshXRFTyetjuotptbxYDGPkljraWOVHVo/ShZb7C/Q36Y1Eb0y8DZikbmSQ0BdtA3YG2oDza5++FtqiMjwBSkTbm2x+ex7bbe+HzfQmC7Ni51jUO4JwNJDUTOY4YZJnKiyxqWJ/Qb+cZeqqMwpXEUVTOUGyaWJt5F/pixyGHiLN6qnpaSTM6nnOY1ETOUVrXINthtvhbaQ1JsdWX5NB8IryH8Yxct55otMjKCbaioUk7N9fOCKDJJKapGutnmp0J5cbvbQD/DcC5A9ycWSQQ2ASPSRYXJ6WAG36AY+llWIab2OI4xvkocqJp6lYU9Fr9jiknk5rEs51eb4kmkMlz08b4Ake5svp9wMPWEKeSOdVBDC9u+5vjOZ5JDXVkuWVMjJGqRzRgSEEfmF/azA/bF5UsVXb1HsO98KDifM8yi4qZ6saXpwUUKAPwjcgXHXY9cEsgvBbywRZVmUa1UoNLUKw5sRUFhboQdr79dvN8WFdwrG8UL0zGm1rtFIis58nrYD379r4zVPK+a0FDTo5Z6X0shHqZDYLbz2wySkFO0sqUtUsAH+58LKVA9yVt98LnKUfkZFRksmbi4RKwrG88Ug6+uMNb5XBtg9cjrjTpTfvWVKZPyRRAIoPmwUb4lj4py+ncqkvOudwsRY7eNsTjiSGtTRDRVhMZ3EVI5P9sKcptWw0ksIY7uEUjxgCYcwnUzdb9SBiebVsLi5FyMBST8liD9cOSFNnh3VV3NgO4wO6gnVcW97HErFpV6sU7X2wOQeZ6XAFrkWxpwNUR3Fg2m+xAG5/8wmOKcsbLeIqqAs7IxEiGQktY+SfBuP0w6qtElglhErozoVDRmzrt1B84WNbwNOHZ6aqEtybicFWJ+e9/tgtPDyDLgreDc5GS8Rw1gLCSNPSOzEW6+1rn5gYc8f7Rp6mMcyTUrC40sN/a1r/AHthBGmaGQOZFimjb8rBtSkfpbHss0xZ/jxCAQNCc0326ja39sFOMn8uinxdfR0r9umpDrrs5yqqgSKcz06K2q0AWPe1uq2Nt8B0ecZDldUamOprjMLhWNQo2PXdsKFMuhmN/iKmRj/JSlr/AFYYKhyJmay0uZMewWi6/wDbCvU7tst/J6cY7YaSS/f8P//Z";

Source: Convert Image to Base64 String and Base64 String to Image

string applicationPath = Page.Request.ApplicationPath;

if (!Page.Request.ApplicationPath.EndsWith("/"))

  {

     applicationPath = string.Format("{0}{1}", Page.Request.ApplicationPath, "/");

  }

string helpUrl = string.Format("{0}{1}", Page.Request.Url.Scheme + "://" + Page.Request.Url.Authority + applicationPath, "Help/GlobalSearch.htm");

//Add CSS File
Page.Header.Controls.Add(new LiteralControl("<link href='style.css' rel='stylesheet' type='text/css' />"));

//Add JavaScript file
ClientScript.RegisterClientScriptInclude("javascriptfile", ResolveUrl("~/javascript.js"));

1. <a href="Update.aspx?Key=<%# String.Format("{0}&uMode={1}", HttpUtility.UrlEncode(Eval("Key").ToString()), base.UserMode) %>" style="display:'<%# SetLinkVisibility() %>';">  <%# Eval("Key") %> </a>

2. <%# FormatDate(Eval("StartDate").ToString())%>

3.  <%# ((DateTime)Eval("ClientDetail.DateOfBirth")).ToString("dd-MMM-yyyy")%>

4.  var counter = document.getElementById('<%= txtCounter.ClientID %>');

• ASP.NET Tip/Trick: Use a Base Page Class for All Application Pages
• Reading embedded files at runtime
• Embedding JavaScript and Other Resources In a .NET Assembly
• Implementing A Value Object With NHibernate
• Implementing Incremental Navigation with ASP.NET
• Syndicating and Consuming RSS 1.0 (RDF) Feeds in ASP.NET 3.5
• The Page Life Cycle Events

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