How to get SP.Folder for SP.ListItem in SharePoint 2010 JavaScript Client Object Model?

Question

I have a custom button on ribbon for document library and need to disable it if current SPListItem is an empty folder.

To disable button I use EnabledScript attribute of CommandUIHandler. I can get current SP.ListItem in JS COM by next code:

var clientContext = new SP.ClientContext();
var list = clientContext.get_web().get_lists().getById({ListID});  
var item = list.getItemById({ItemID});

And then I can detect if item is folder or file by its SP.ListItem.fileSystemObjectType Property

var fsoType = item.get_fileSystemObjectType();

And in case of File I can get file by SP.ListItem.file property. But I can't get SP.Folder if fsoType is Folder. How could I get it?

Then simply I could check SP.Folder.files and SP.Folder.folders roperties.

Answer 1

You can get all the folders with the following:

function GetFolders() {
  var context = new SP.ClientContext.get_current();
  var web = context.get_web();
  var list = web.get_lists().getByTitle('DocumentLibraryName');
  var query = SP.CamlQuery.createAllFoldersQuery();
  var allItems = list.getItems(query);
  context.load(allItems);
  context.executeQueryAsync(Function.createDelegate(this, this.success), 
      Function.createDelegate(this, this.failed));
}

function success() {
  var FolderNames = "";
  var ListEnumerator = this.allItems.getEnumerator();
  while (ListEnumerator.moveNext()) {
    var currentItem = ListEnumerator.get_current();
    var _contentType = currentItem.get_fileSystemObjectType();
    if(currentItem.get_fileSystemObjectType() == '1') {
      FolderNames  += currentItem.get_item('Title')+ '\n';
    }
  }
  alert(FolderNames);
}

function failed(sender, args) {
  alert("failed. Message:" + args.get_message());
}

Answer 2

If fsoType = Folder then I guess item is the SP.Folder already and you can use item.get_files();

Before you try to get those properties a clientContext.executeQueryAsync() is needed.

Answer 3

You need to check the value of the item.get_fileSystemObjectType();

Here are all the possible values: http://msdn.microsoft.com/en-us/library/microsoft.sharepoint.client.filesystemobjecttype.aspx