Tree View WebPart for Sharepoint List Data

Introduction

This article provides you with the code snippet to display a SharePoint list data as a tree view WebPart.

Background

The code creates a tree view control and then populates it with various folders and subfolders from a given list. To access the subfolders of the list, an SPQuery variable is used. The list item is first checked with a condition (listitem.Folder == null) to determine whether it is a folder or a list item. The GetItems recursive method is then called to get the list item or the items in the folder.

Using the code

The code displays data from a "Links" type custom list called "All Programs" as a tree view. The CreateChildControl method calls the GetFolder method to access the subfolders of the list. The GetFolder method further calls the GetItems method to get the items or subfolders in a subfolder. GetItems uses SPquery to get the items in a folder and is called recursively to get the items in subfolders of a folder.

public class WebPart1 : System.Web.UI.WebControls.WebParts.WebPart
{
    TreeView treeView;
    TreeNode rootNode;

    public WebPart1()
    {
    }

    protected override void RenderContents(System.Web.UI.HtmlTextWriter writer)
    {
        // render the control
        base.RenderContents(writer);
    }

    protected override void CreateChildControls()
    {
        base.CreateChildControls();

        // get the current site
        SPSite currentSite = SPContext.Current.Site;
        using (SPWeb currentWeb = currentSite.OpenWeb())
        {
            // set the tree view properties
            treeView = new System.Web.UI.WebControls.TreeView();
            treeView.ShowLines = true; // show lines
            treeView.ExpandDepth = 0; // expand non

            SPList list = currentWeb.Lists["All Programs"];

            // build the tree
            rootNode = new System.Web.UI.WebControls.TreeNode(list.Title, "", 
                       "", list.RootFolder.ServerRelativeUrl.ToString(), "");

            // loop down the tree
            GetFolder(list.RootFolder, rootNode, list);

            // add the root node to tree view
            treeView.Nodes.Add(rootNode);
        }
        this.Controls.Add(treeView);
        base.CreateChildControls();
    }

    public void GetFolder(SPFolder folder, TreeNode rootNode, SPList list)
    {
        // create a new node
        TreeNode newNode = new System.Web.UI.WebControls.TreeNode(folder.Name, "", 
                           "~/_layouts/images/itdl.gif", 
                           folder.ServerRelativeUrl.ToString(), "");
        try
        {
            // don't add the forms folder
            if (folder.Name != "Link")
            {
                // loop through all child folders
                foreach (SPFolder childFolder in folder.SubFolders)
                {
                    // don't add the forms folder
                    if (childFolder.Name != "Link")
                    {
                        TreeNode trn = 
                          new System.Web.UI.WebControls.TreeNode(childFolder.Name, "", 
                          "", childFolder.ServerRelativeUrl.ToString(), "");
                        newNode = GetItems(childFolder, trn);

                        // add the new node to the tree
                        rootNode.ChildNodes.Add(newNode);
                    }
                }
            }
        }
        catch { }
    }

    public TreeNode GetItems(SPFolder folder, TreeNode node)
    {
        //Get Items from childFolder
        SPQuery qry = new SPQuery();
        qry.Folder = folder;
        SPWeb web = null;

        web = folder.ParentWeb;
        SPListItemCollection ic = web.Lists[folder.ParentListId].GetItems(qry);

        foreach (SPListItem subitem in ic)
        {
            if (subitem.Folder != null) //Is Subfolder
            {
                // create a new node for a subfolder and add items to it
                TreeNode childNode = 
                  new System.Web.UI.WebControls.TreeNode(subitem.Folder.Name);
                node.ChildNodes.Add(GetItems(subitem.Folder, childNode));
            }  

            if (subitem.Folder == null)
            {
                TreeNode trn1 = new System.Web.UI.WebControls.TreeNode(
                                      subitem["Title0"].ToString());
                node.ChildNodes.Add(trn1);
            }
        }
        return node;
    }
}

In the above code, SPquery is used to get the items from a given folder since there is no other way to get items from a list of subfolders as item.folder does not expose subfolders.

For any comments and questions on this article, please visit my blog: http://mysharepointwork.blogspot.com/2009/09/tree-view-webpart-for-list-data.html.