Scaling jsTree performance

Question

I am using jsTree v1.0 (latest v3.0, they withdraw support from older versions) to display the hierarchy in my application. It was good until until I started showing groups/user up to 200 levels, but now I have a new client which has levels as big as up to 5000, so this code is taking too long to execute. I have two options: either I switch to new plugin (time taking) or optimize the existing code which I am using.

public static List<JsTreeNode> NodeList(DataTable dtMainGroup, DataTable dtMainUser, bool includeUsers)
{
    List<JsTreeNode> nodeList = new List<JsTreeNode>();
    List<String> LStrGpId = new List<string>();
    List<String> LStrChild = new List<string>();

    DataView dvGroup = new DataView();
    DataView dvUser = new DataView();

    dvGroup = dtMainGroup.DefaultView;
    dvUser = dtMainUser.DefaultView;

    if (dtMainGroup.Rows.Count > 0)
    {
        for (int i = 0; i < dtMainGroup.Rows.Count; i++)
        {
            DataRow drMain = dtMainGroup.Rows[i];
            if (!LStrGpId.Contains(Convert.ToString(drMain["GroupId"])) && !LStrChild.Contains(Convert.ToString(drMain["GroupId"])))
            {
                if (i == 0)
                {
                    selectedGroup = Convert.ToString(drMain["GroupId"]);
                }
                JsTreeNode node = new JsTreeNode();
                node.attr = new Attributes();
                node.attr.id = Constants.GroupPrefix + Convert.ToString(drMain["GroupId"]);
                node.attr.rel = Constants.treeNodeRelFolder;
                node.data = new Common.Data();
                node.data.title = Convert.ToString(drMain["Name"]);
                node.data.state = Constants.treeNodeStateClosed;

                LStrGpId.Add(Convert.ToString(drMain["GroupId"]));
                node.children = new List<JsTreeNode>();
                if (includeUsers)
                {
                    node = GetUser(dvUser, dvGroup, drMain, node);
                }
                node = GetChild(dvGroup, dvUser, drMain, node, LStrChild, includeUsers);

                nodeList.Add(node);
            }
        }
    }
    return nodeList;
}

public static JsTreeNode GetUser(DataView dvUsr, DataView dvGp, DataRow dr, JsTreeNode node)
{
    dvUsr.RowFilter = "GroupId = '" + Convert.ToString(dr["GroupId"]) + "'";
    if (dvUsr.Count > 0)
    {
        DataTable dtUser = new DataTable();
        dtUser = dvUsr.ToTable();
        for (int k = 0; k < dtUser.Rows.Count; k++)
        {
            DataRow drUser = dtUser.Rows[k];
            JsTreeNode cnode = new JsTreeNode();
            cnode.attr = new Attributes();
            cnode.attr.id = Constants.EmployeePrefix + Convert.ToString(drUser["UserID"]);
            cnode.attr.rel = Constants.treeNodeRelDefault;
            cnode.data = new Common.Data();
            cnode.data.title = Convert.ToString(drUser["FirstName"]);
            cnode.data.state = Constants.treeNodeStateClosed;

            node.children.Add(cnode);
        }
    }
    return node;
}

public static JsTreeNode GetChild(DataView dvGp, DataView dvUsr, DataRow dr, JsTreeNode node, List<string> LStrChild, bool includeUsers)
{
    dvGp.RowFilter = "ParentGroupId = '" + Convert.ToString(dr["GroupId"]) + "'";

    if (dvGp.Count > 0)
    {
        DataTable dtChild = new DataTable();
        dtChild = dvGp.ToTable();

        for (int j = 0; j < dtChild.Rows.Count; j++)
        {
            DataRow drChild = dtChild.Rows[j];

            LStrChild.Add(Convert.ToString(drChild["GroupId"]));

            JsTreeNode cnode = new JsTreeNode();
            cnode.attr = new Attributes();
            cnode.attr.id = Constants.GroupPrefix + Convert.ToString(drChild["GroupId"]);
            cnode.attr.rel = Constants.treeNodeRelFolder;
            cnode.data = new Common.Data();
            cnode.data.title = Convert.ToString(drChild["Name"]);
            cnode.data.state = Constants.treeNodeStateClosed;
            cnode.children = new List<JsTreeNode>();
            if (includeUsers)
            {
                cnode = GetUser(dvUsr, dvGp, drChild, cnode);
            }
            cnode = GetChild(dvGp, dvUsr, drChild, cnode, LStrChild, includeUsers);

            node.children.Add(cnode);
        }
    }
    return node;
}

Answer 1

I don't think you'll find a single line of C# or JavaScript that will make this run faster. You need lazy loading. When the page first loads, load just the first two levels. Then clicking on a level will load the next level.

If the data in the database doesn't change very often, cache the HTML snippets sent back to the browser for a bigger boost to performance. There are only so many code changes you can make before you are just plain old trying to process to much data at once.

Answer 2

I'm not great at answering performance queries, but I'll address the other aspects of your code.

Naming

Your casing is fine here, but I would avoid using Hungarian notation. You can get your point across fine without it.

So:

DataView dvGroup = new DataView();

becomes:

DataView group = new DataView();

Additionally, you should avoid including type information in a variable name. If you come to change the type, you'll have to be sure to change the name too.

So:

List<JsTreeNode> nodeList = new List<JsTreeNode>();

Should become:

List<JsTreeNode> nodes = new List<JsTreeNode>();

Declaration

Prefer to use var when the right-hand side of a variable declaration makes its type obvious. This way, should you need to change the type, you only have to do it once.

So:

List<JsTreeNode> nodeList = new List<JsTreeNode>();

Should be:

var nodeList = new List<JsTreeNode>();

Additionally, you can make your code more concise by using Object Initializers, so:

node.attr = new Attributes();
node.attr.id = Constants.GroupPrefix + Convert.ToString(drMain["GroupId"]);
node.attr.rel = Constants.treeNodeRelFolder;

becomes:

node.attr = new Attributes()
{
    id = Constants.GroupPrefix + Convert.ToString(drMain["GroupId"]),
    rel = Constants.treeNodeRelFolder
};

Magic Strings

I'm seeing a couple of magic strings here and there, that should be constants somewhere in your solution.

e.g.

node.attr.id = Constants.GroupPrefix + Convert.ToString(drMain["GroupId"]);

Here "GroupId" should be assigned to a constant variable with a descriptive name, so that it can be changed centrally and also offer a better clue as to its purpose.