How do I get the 'CheckedOutByUser' in SharePoint 2013

Question

I am updating a document and I try to check it out first. If it is already checked out by the current user I do nothing. If it is not checked out I check it out. For this I have the following code to get the checked out user -

var item = list.GetItemById(ItemId);
clientContext.Load(item.File, f => f.CheckedOutByUser.LoginName);
clientContext.ExecuteQuery();

Since the document is not checked out the server side object is null and 'ClientObject.m_setAsNull' base member is set to true. After checking out the document I try to get the 'CheckedOutByUser.LoginName' value using the following code

var item = list.GetItemById(ItemId);
clientContext.Load(item.File.CheckedOutByUser);
clientContext.ExecuteQuery();

This loads all the scalar properties of the 'User' object but the 'ClientObject.m_setAsNull' is not reset to false. Hence even though the LoginName property exists in the internal dictionarty I get the ServerObjectNullReferenceException.

Any idea how I should achieve what I want - Get the checkedout user when the value was null previously?

Answer 1

The code that you have provided works for me in SharePoint 2013.

You could also try to retrieve Checkout User by Id:

context.Load(item);
context.ExecuteQuery();
var checkoutUserValue = item["CheckoutUser"] as FieldUserValue;
if (checkoutUserValue != null)
{
     var checkoutUser = context.Site.RootWeb.GetUserById(checkoutUserValue.LookupId);
     context.Load(checkoutUser);
     context.ExecuteQuery();
     Console.WriteLine(checkoutUser.LoginName);
}

How to determine CSOM version

using (var context = new ClientContext(url))
{             
      context.ExecuteQuery();
      if (context.ServerVersion.Major == 16)
      {
           Console.WriteLine("SharePoint Online CSOM");
      }
}