Exception when loading Folder from ListItem

[FelgeIO]

Category

• Bug

Describe the bug

An exception is thrown when properties of a Folder - that is represented by a ListItem - are loaded and/or accessed:

Specify the GraphGet/GraphGetLinq field of the ClassMapping property

Steps to reproduce

The following method can be used to reproduce the issue (provided that at least one ListItem representing a Folder is contained within the list):

public async Task GetFolderChanges(IList list)
{
    var queryOptions = new ChangeQueryOptions() { Add = true, Update = true, Item = true };
    IList<IChange> listChanges = list.GetChanges(queryOptions);

    foreach (var listChange in listChanges)
    {
        if (listChange is IChangeItem changeItem)
        {
	    var itemId = changeItem.ItemId;
            var listItem = list.Items.GetById(itemId);

            if (listItem.IsFolder())
            {
                // Option 1:
                try
                {
                    var folder = await listItem.Folder.GetAsync(f => f.ServerRelativeUrl, f => f.Name, f => f.TimeLastModified);
                    // do something with folder
                }
                catch (Exception ex)
                {
                    // Exception: "Specify the GraphGet/GraphGetLinq field of the ClassMapping property"
                }

                // Option 2:
                try
                {
                    var folder = listItem.Folder;
                    await folder.LoadAsync(f => f.ServerRelativeUrl, f => f.Name, f => f.TimeLastModified);
                    // do something with folder
                }
                catch (Exception ex)
                {
                    // Exception: "Specify the GraphGet/GraphGetLinq field of the ClassMapping property"
                }
            }
        }
    }
}

Presumably, one could also just iterate over a list to find a Folder in order to reproduce the issue .. I simply stumbled upon this while writing some code to process changes of a list.

Expected behavior

When the above code is run for a ListItems representing Files (listItem.IsFile() + listItem.File), everything works as expected: The requested properties (ServerRelativeUrl, Name, TimeLastModified) are loaded correctly and can be accessed. I expect that this would also be the correct behavior for ListItems representing Folders .. but instead, an exception is thrown.

Environment details

• SDK version: 1.6.0
• OS: Windows 10
• SDK used in: Azure Function App (dotnet-isolated)
• Framework: .NET Framework 6.0
• Tooling: Visual Studio 2022

Additional context

The logs show that the exception is thrown before the request is even sent to SharePoint.

[jansenbe]

Thanks @FelgeIO for using PnP Core SDK and logging this issue...and fix for it 👍

[jansenbe]

@FelgeIO : fix has been merged and will appear in next nightly (1.6.7). Thanks for providing this. Will close the issue now, but don't hesitate to re-open or create a new one in case you still experience an issue.