How to check if a folder exists in a list?

Question

I have the following code:

SPFolder oFolder = myList.RootFolder.SubFolders[folderName];
            if (oFolder == null)
            {
                Console.WriteLine("FOLDER NOT FOUND"); 
            }
            else
            {
                Console.WriteLine("FOLDER FOUND"); 
            }

Looks good on the surface but it only works if the folder exists, if the folder doesn't exist it throws an object reference not set to an instance error.

Is there a better way to check if a folder exists (without iterating through every folder in a collection?

Answer 1

Try this...

public bool FolderExists(string url, SPWeb web)
    {
      try
      {
        //Check folder exist in the SPWeb or not

        if (web.GetFolder(url).Exists)
        {
          return true;
        }
        return false;
      }
      catch (ArgumentException ex)
      {
        return false;
      }
      catch (Exception ex)
      {
        return false;

      }
    }

Answer 2

The SPFolderCollection (which is returned by RootFolder) will throw an exception when queried for a non-existing folder. You can catch that Exception (an ArgumentException) or test it with a function like this:

private bool CheckFolderExists(SPWeb parentWeb, string folderName)
{
  SPFolder folder = parentWeb.GetFolder(folderName);
  return folder.Exists
}

^{use for the parameter folderName something like: "ListName/FolderName/SubFolderName"}

Answer 3

Or you can try this...

public bool FolderExists(string url, SPWeb web)
    {
      try
      {
        //Check folder exist in the SPWeb or not

        if (web.GetFolder(url).Exists)
        {
          return true;
        }
        return false;
      }
      catch (ArgumentException ex)
      {
        return false;
      }
      catch (Exception ex)
      {
        return false;

      }
    }

Answer 4

You can create an extension method like this to check for the folder existance, and if exists you get the SPFolder in the output parameter.

SPFolderCollection[string] throw an ArgumentException if not exists so if might be faster ways to do this like using a CAML query, but here is a suggestion.

public static class SPFolderCollectionExtensions
{
    public static bool TryGetFolder(this SPFolderCollection instance, string folderName, out SPFolder folder)
    {
        try
        {
            folder = instance[folderName];

            if (!folder.Exists)
            {
                folder = null;
                return false;
            }

            return true;
        }
        catch (ArgumentException)
        {
            folder = null;
            return false;
        }
    }
}