Filter out hidden folder using client object model in sharepoint 2013

Question

I am adding list and library in treeview but it also displaying the "Forms", "Attachements", "Item" hidden folder in treeview.

Any one has any idea to hide that folder using client object model?

I'm using below code:

public static List<FolderInfo> GetFoldersInFolder(Folder folder, Web web, ClientContext clientContext) {
    List<FolderInfo> result = new List<FolderInfo>();
    FolderInfo folderinfo;
    FolderCollection subFolders = folder.Folders;clientContext.Load(folder);
    clientContext.Load<FolderCollection>(s‌​ubFolders);
    clientContext.ExecuteQuery();
    foreach (Folder subFolder in subFolders){
        folderinfo = new FolderInfo();
        folderinfo.Name = subFolder.Name;
        folderinfo.URL = subFolder.ServerRelativeUrl;
        result.Add(folderinfo);
    }
    return result;
}

Answer 1

How to exclude "system" folders using SharePoint CSOM

Folder class exposes Folder.ListItemAllFields property that specifies the list item associated with the folder, for "system" folders the corresponding list item does not exist.

The following example demonstrates how to verify whether the folder is regular or "system" folder:

bool regularFolder = subFolder.ListItemAllFields.ServerObjectIsNull != null && !subFolder.ListItemAllFields.ServerObjectIsNull.Value;

Fixed example

public static List<FolderInfo> GetFoldersInFolder(Folder folder, Web web)
{
    var ctx = web.Context as ClientContext;
    var result = new List<FolderInfo>();
    ctx.Load(folder.Folders, fcol => fcol.Include(f => f.Name, f => f.ServerRelativeUrl, f => f.ListItemAllFields));
    ctx.ExecuteQuery();
    foreach (var subFolder in folder.Folders)
    {
            if (subFolder.ListItemAllFields.ServerObjectIsNull != null && !subFolder.ListItemAllFields.ServerObjectIsNull.Value)
            {
                var folderinfo = new FolderInfo {Name = subFolder.Name, URL = subFolder.ServerRelativeUrl};
                result.Add(folderinfo);    
            }
    }
    return result;
}