SharePoint item.File - ServerObjectNullReferenceException

Question

I'm attempting to load information about all File Items in a list. In this snippet, item refers to a ListItem

switch(item.FileSystemObjectType)
            {
                case FileSystemObjectType.File:
                    if (ListOptions.IndexFileItems)
                    {
                        ClientContext.Load(item, i => i.File);
                        ClientContext.ExecuteQuery();
                        if (item.File.Exists)

When the code is run, it reaches the final line and then throws ServerObjectNullReferenceException.

I do not understand this, as the item has declared itself to be of Type File in it's FileSystemObjectType, should I not expect the Fileproperty to have a reference, having loaded it? Am I loading the file incorrectly?

Answer 1

ListItem.File is used in document library, please make sure list object is a library:

ListItem.File property

I tested the code snippet below, work as expected:

            ClientContext ctx = new ClientContext("http://sp/sites/dev/");
            List list = ctx.Web.Lists.GetByTitle("dccc");
            CamlQuery caml = new CamlQuery();
            ListItemCollection items = list.GetItems(caml);
            ctx.Load(items);
            ctx.ExecuteQuery();
            foreach (ListItem item in items)
            {

                switch (item.FileSystemObjectType)
                {
                    case FileSystemObjectType.File:
                        ctx.Load(item, i => i.File);
                        ctx.ExecuteQuery();
                        if (item.File.Exists)
                        {
                            Console.WriteLine(item.File.Name);
                        }
                        break;
                }
            }

So the files are two jpg file: