Error with TreeView in Web Part

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Error with TreeView in Web Part

I'm attempting to create a custom web part that will display information using a TreeView.  I'm able to retrieve the required information without any problems as I can render it in raw text.  When I attempt to use a TreeView I can render the control, but I'm not able to expand any of the nodes (or collapse them if I make them expanded by default) instead I get an error message stating that "Problem with this Web page might prevent t from being displayed properly or functioning properly."  The details of the error are as follows:

Line: 1
Char: 1
Error: Object Expected
Code: 0
Url: The url of the page I'm viewing

I've reduced the Web Part to just creating a simple TreeView and rendering it, my code is as follows:

public class MyTreeView : System.Web.UI.WebControls.WebParts.WebPart
{
    protected override void Render(HtmlTextWriter writer)
    {
        SPTreeView t = new SPTreeView();
        this.Controls.Add(t);
        t.Nodes.Add(new System.Web.UI.WebControls.TreeNode("Top 1"));
        t.Nodes[0].ChildNodes.Add(new System.Web.UI.WebControls.TreeNode("Sub 1"));
        t.Nodes[0].ChildNodes.Add(new System.Web.UI.WebControls.TreeNode("Sub 2"));
        t.RenderControl(writer);
    }
}
 
I've also tried using the normal TreeView class from System.Web.UI.WebControls with the same result.

I'm hoping someone can point out to me what I'm missing, thanks!

Answer this question

Error with TreeView in Web Part

  • mstep100

    I too had the same problem . Thing is js expecting some object . real y i don't know which object it's requesting. But wt i did is I have created and rendered one more TreeView ASP.NET control which ll provide that object. My Code is

    here tv is no use other than providing that Java script Object ( which is in the js error message )

    Button btnSave;

    SPTreeView sptv; // Our Display control

    TreeView tv; // Dummy

    TreeNode treenode;

    TreeNode tn;

    SPList list;

    SPWeb _web;

    protected override void CreateChildControls()

    {

    base.CreateChildControls();

    tv = new TreeView(); // Dummy Tree view asp.net control

    Controls.Add(tv);

    sptv = new SPTreeView(); // Our Tree view to display

    btnSave = new Button();

    btnSave.Text = "Save" ;

    btnSave.Click += new EventHandler(btnSave_click);

    Controls.Add(btnSave);

    }

    protected override void Render(HtmlTextWriter writer)

    {

    GetTreeView(); // Function to Fill all Nodes in to the SPTreeView control

    Controls.Add(sptv); // Adding to the page

    sptv.RenderControl(writer); // Rendering

    tv.RenderControl(writer); // Dummy asp.net control

    writer.Write("<br><br>");

    btnSave.RenderControl(writer);

    }

    This code is working for me...

    Chees

    Moorthy .A

    India.


  • Fiddel

    Figured it out, apologies for the delayed reply. One thing to keep in mind with web parts is what actions you're performing at which stage. In this instance I was doing everything during the render phase. Instead I should be creating the TreeView and populating it earlier during the rendering stage, for instance you can do it within the CreateChildControls stage.

  • Andrei Faber

    I have had the same problem, but i added the following lines before RenderControl

    t.ID = "MyTree1";
    t.SkipLinkText = "";

  • M. Nicholas

    I'm currently experiencing the same problem. If anyone has any fix for this, I'd be extremely grateful.

    // Eric

  • ScaryKidsScaringKids

    I never tried, but my guess is that the treeview is expecting you to override more functions

  • Rahul Singla

    Hello McGuire,

    I am facing an error "Object expected" which sounds similar to your issue. Here is what i am trying to do:

    - Add the treeview control in RenderControl method.

    - Build the treeview in CreateChildControls method

    However, clicking any of the nodes in the treeview does result in this javascript error.

    Is there any other way of resolving the issue

    Thanks in advance,

    Regards,

    Siku
  • Error with TreeView in Web Part
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