TreeListVirtualModeCreateChildrenEventArgs Class

Provides data for the ASPxTreeList.VirtualModeCreateChildren event.

Namespace: DevExpress.Web.ASPxTreeList

Assembly: DevExpress.Web.ASPxTreeList.v19.2.dll

Declaration

public class TreeListVirtualModeCreateChildrenEventArgs :
    EventArgs
Public Class TreeListVirtualModeCreateChildrenEventArgs
    Inherits EventArgs

Examples

In this example, the ASPxTreeList uses the Virtual data binding method to display the file/folder tree. In this mode, a tree is created on demand.

The image below shows the result.

exVirtualMode

using System.IO;
using System.Collections.Generic;
using DevExpress.Web.ASPxTreeList;

protected void ASPxTreeList1_VirtualModeCreateChildren(object sender,
TreeListVirtualModeCreateChildrenEventArgs e) {
    string path = e.NodeObject == null ? Page.MapPath("~/") : e.NodeObject.ToString();

    List<string> children = new List<string>();
    if (Directory.Exists(path)) {
        foreach (string name in Directory.GetDirectories(path)) {
            if (!IsSystemName(name))
                children.Add(name);
        }
        foreach (string name in Directory.GetFiles(path))
            if (!IsSystemName(name))
                children.Add(name);
    }
    e.Children = children;
}
protected void ASPxTreeList1_VirtualModeNodeCreating(object sender,
TreeListVirtualModeNodeCreatingEventArgs e) {
    string path = e.NodeObject.ToString();

    e.NodeKeyValue = GetNodeGuid(path);
    e.IsLeaf = !Directory.Exists(path);
    e.SetNodeValue("FileName", PopFileName(path));
}

// Helpers

Guid GetNodeGuid(string path) {
    if (!Map.ContainsKey(path))
        Map[path] = Guid.NewGuid();
    return Map[path];
}
Dictionary<string, Guid> Map {
    get {
        const string key = "DX_PATH_GUID_MAP";
        if (Session[key] == null)
            Session[key] = new Dictionary<string, Guid>();
        return Session[key] as Dictionary<string, Guid>;
    }
}
string PopFileName(string path) {
    return path.Substring(1 + path.LastIndexOf("\\"));
}
bool IsSystemName(string name) {
    name = PopFileName(name).ToLower();
    return name.StartsWith("app_") || name == "bin"
        || name.EndsWith(".aspx.cs") || name.EndsWith(".aspx.vb");
}

Inheritance

Object
EventArgs
TreeListVirtualModeCreateChildrenEventArgs
See Also