Javascript wont do a postback from c# code in asp.net

Ok managed to get the code working, as in no errors but it wont do a post back after ive confirmed when I click on the div?:

<script type="text/javascript">
    function confirm_delete(id){
        if (confirm('Are you sure you want to delete?')) {
            __doPostBack('DivClicked', id);
        }
        else {
            return false;
        }
    }

Code behind:

public partial class UserProfileWall : System.Web.UI.Page
{

    protected void Page_Load(object sender, EventArgs e)
    {
        if (Page.IsPostBack)
        {
            //It is a postback so check if it was by div click (NOT WORKING because the javascript isnt posting back)
            string target = Request["__EVENTTARGET"];
            if (target == "DivClicked")
            {
                string id = Request["__EVENTARGUMENT"];
                //Call my delete function passing record id
                Response.Write(String.Format(id)); //just a test 
            }
        }
        string theUserId = Session["UserID"].ToString();
        PopulateWallPosts(theUserId);
    }
    private void PopulateWallPosts(string userId)
    {

        using (OdbcConnection cn = new OdbcConnection("Driver={MySQL ODBC 3.51 Driver}; Server=localhost; Database=gymwebsite2; User=root; Password=commando;"))
        {
            cn.Open();
            using (OdbcCommand cmd = new OdbcCommand("SELECT idWallPosting, wp.WallPostings, p.PicturePath FROM WallPosting wp LEFT JOIN User u ON u.UserID = wp.UserID LEFT JOIN Pictures p ON p.UserID = u.UserID WHERE wp.UserID=" + userId + " ORDER BY idWallPosting DESC", cn))
            {
                //("SELECT wp.WallPostings, p.PicturePath FROM WallPosting wp LEFT JOIN [User] u ON u.UserID = wp.UserID LEFT JOIN Pictures p ON p.UserID = u.UserID WHERE UserID=" + userId + " ORDER BY idWallPosting DESC", cn))
                using (OdbcDataReader reader = cmd.ExecuteReader())
                {
                    test1.Controls.Clear();

                    while (reader.Read())
                    {

                        System.Web.UI.HtmlControls.HtmlGenericControl div = new System.Web.UI.HtmlControls.HtmlGenericControl("div");
                        div.Attributes["class"] = "test";


                        div.ID = String.Format("{0}", reader.GetString(0));
                        string id = Convert.ToString(div.ID);
                        //store the div id as a string
                        Image img = new Image();
                        img.ImageUrl = String.Format("{0}", reader.GetString(2));
                        img.AlternateText = "Test image";

                        div.Controls.Add(img);
                        div.Controls.Add(ParseControl(String.Format("&nbsp&nbsp&nbsp;" + "{0}", reader.GetString(1))));
                        div.Attributes.Add("onclick", "return confirm_delete(" + id + ");");
                        // send the div id to javascript
                        div.Style["clear"] = "both";
                        test1.Controls.Add(div);

                    }
                }
            }
        }
    }



    protected void Button1_Click(object sender, EventArgs e)
    {
        string theUserId = Session["UserID"].ToString();
        using (OdbcConnection cn = new OdbcConnection("Driver={MySQL ODBC 3.51 Driver}; Server=localhost; Database=gymwebsite2; User=root; Password=commando;"))
        {
            cn.Open();
            using (OdbcCommand cmd = new OdbcCommand("INSERT INTO WallPosting (UserID, Wallpostings) VALUES (" + theUserId + ", '" + TextBox1.Text + "')", cn))
            {
                cmd.ExecuteNonQuery();
            }
        }
        PopulateWallPosts(theUserId);
    }
}

Any Reason why the code isnt executing a postback?

Answers:

Answer

The problem is because __doPostBack is not defined. It's not defined because you didn't put any control on your page that is a an IPostBackEventHandler, like LinkButton is.

In order to Page.IsPostBack to be true, you have to either:

  • Re-archtecture your application so that you implement a control that implements IPostBackEventHandler and, of course, put it on your page
  • You put a dummy IPostBackEventHandler on your page. One that doesn't do anything. Like a LinkButton.

Either way ASP.NET will define the __doPostBack function at client side and your code will finally postback

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