SharePoint: Working with SharePoint Permissions in Client Object model

A user asked the following question:
I have SharePoint List with unique permissions. I need to retrieve the SharePoint Groups which don't have Full Control permissions on the List. Then need to remove them from the List Permissions only.
Since I was free I thought to give it a try. Following is the code:

ClientContext clientContext = new ClientContext("http://demo2010a:90");
Web site = clientContext.Web;
List list = clientContext.Web.Lists.GetByTitle("TestList");
clientContext.Load(site, s => s.RoleDefinitions);
clientContext.ExecuteQuery();
clientContext.Load(list, l => l.HasUniqueRoleAssignments);
clientContext.ExecuteQuery();
List<Principal> groupsToRemove = new List<Principal>();           
if (list.HasUniqueRoleAssignments)
{
    RoleDefinition role = site.RoleDefinitions.GetByName("Full Control");
    clientContext.Load(role);
    clientContext.ExecuteQuery();
    RoleAssignmentCollection oRoleAssignments = list.RoleAssignments;
    clientContext.Load(oRoleAssignments);
    clientContext.ExecuteQuery();
    List<RoleDefinition> rolesToRemove = new List<RoleDefinition>();
    foreach (RoleAssignment oRoleAssignment in oRoleAssignments)
    {
        clientContext.Load(oRoleAssignment, r => r.Member, r => r.RoleDefinitionBindings);
        clientContext.ExecuteQuery();
        Principal oPrincipal = oRoleAssignment.Member;
        if (oPrincipal.PrincipalType == Microsoft.SharePoint.Client.Utilities.PrincipalType.SharePointGroup)
        {
            int roleDefCount = 0;
            foreach (RoleDefinition def in oRoleAssignment.RoleDefinitionBindings)
            {
                if (def.Id == role.Id)
                {                               
                    break;
                }
                else
                {
                    roleDefCount++;
                    if (roleDefCount == oRoleAssignment.RoleDefinitionBindings.Count)
                        groupsToRemove.Add(oPrincipal);
                }
            }                     
        }
    }

    foreach (Principal group in groupsToRemove)
    {
        list.RoleAssignments.GetByPrincipal(group).DeleteObject();
    }

    list.Update();
}
clientContext.ExecuteQuery();

I actually tried to use a simpler statement i.e.

if (!oRoleAssignment.RoleDefinitionBindings.Contains(role))
{
       groupsToRemove.Add(oPrincipal);
}

But it gives follwoing error: Invalid usage of query execution. The query should be executed by using ExecuteQuery method on the client context object. Anyone having idea why this error comes up?

SharePoint: Working with SharePoint Permissions in Client Object model

Share this