Question

Here is the code I’m using to retrieve the current username from SharePoint 2010 via Silverlight:

ClientContext clientContext = ClientContext.Current;
if (clientContext == null)
{
    SharepointUser = "[Unknown]";
}
else
{
    MessageBox.Show("Beginning server query now...");
    clientContext.Load(clientContext.Web, s => s.CurrentUser);
    clientContext.ExecuteQueryAsync((s, e) =>
    {
        MessageBox.Show("RESPONSE!");
        SharepointUser = clientContext.Web.CurrentUser.LoginName;
        MessageBox.Show("Hello, " + SharepointUser + "!");
    },
    (s, e) =>
    {
        MessageBox.Show("An error occurred: " + e.ToString());
    });
}

The problem is that the request never comes back! The success/error events don’t trigger at all, and the request just seems like it’s going into the void.

Does anyone have any ideas?

Answer 1

MessageBox.Show is probably the cause of the issue. I was having the same issue and by debugging I found that the calls the MessageBox.Show within the ExecuteQueryAsync callbacks were throwing an exception “Invalid cross-thread access”. I needed to wrap the calls like this to get it to work:

Deployment.Current.Dispatcher.BeginInvoke(() => MessageBox.Show("Request Suceeded"));