private static csom.LookupEntry GetRandomLookupEntries(csom.CustomField cf)
 {
     context.Load(cf, c => c, c => c.LookupEntries);
     context.ExecuteQuery();
     try
     {
         Random           r           = new Random();
         int              index       = r.Next(0, cf.LookupEntries.Count);
         csom.LookupEntry lookUpEntry = cf.LookupEntries[index];
         context.Load(lookUpEntry);
         context.ExecuteQuery();
         return(lookUpEntry);
     }
     catch (CollectionNotInitializedException ex)
     {
         return(null);
     }
 }
        /// <summary>
        /// Read and Update Project/Task/Resource custom field values,
        /// this method need a project named "New Project" with a task "New task" and assign to a local resource named "New local resource" already created.
        /// Basically please run CreateProjectWithTaskAndAssignment() before running this to avoid exceptions
        /// </summary>
        public static void UpdateCustomFieldValues()
        {
            // Load csom context
            context = GetContext(pwaInstanceUrl);

            // Create custom field values before read it.
            // CreateCustomFields();

            // Retrive publish project named "New Project"
            // if you know the Guid of project, you can just call context.Projects.GetByGuid()
            csom.PublishedProject project = GetProjectByName(projectName, context);
            if (project == null)
            {
                Console.WriteLine("Failed to retrieve expected data, make sure you set up server data right. Press any key to continue....");
                return;
            }


            if (!project.IsCheckedOut)
            {
            }



            csom.DraftProject draft = project.CheckOut();

            // Retrieve project along with tasks & assignments & resources
            context.Load(draft.Tasks, dt => dt.Where(t => t.Name == taskName));
            context.Load(draft.Assignments, da => da.Where(a => a.Task.Name == taskName &&
                                                           a.Resource.Name == localResourceName));
            context.Load(draft.ProjectResources, dp => dp.Where(r => r.Name == localResourceName));
            context.ExecuteQuery();

            // Make sure the data on server is right
            if (draft.Tasks.Count != 1 || draft.Assignments.Count != 1 || draft.ProjectResources.Count != 1)
            {
                Console.WriteLine("Failed to retrieve expected data, make sure you set up server data right. Press any key to continue....");
                Console.ReadLine();
                return;
            }

            // Since we already filetered and validated that the TaskCollection, ProjectResourceCollection and AssignmentCollection
            // contains just one filtered item each, we just get the first one.
            csom.DraftTask            task       = draft.Tasks.First();
            csom.DraftProjectResource resource   = draft.ProjectResources.First();
            csom.DraftAssignment      assignment = draft.Assignments.First();

            // Retrieve custom field by name
            context.Load(context.CustomFields);
            context.ExecuteQuery();
            csom.CustomField projCF = context.CustomFields.FirstOrDefault(cf => cf.Name == projectCFName);
            csom.CustomField taskCF = context.CustomFields.FirstOrDefault(cf => cf.Name == taskCFName);
            csom.CustomField resCF  = context.CustomFields.FirstOrDefault(cf => cf.Name == resourceCFName);

            // Get random lookup table entry
            csom.LookupEntry taskLookUpEntry = GetRandomLookupEntries(taskCF);

            // Change project custom field value
            draft[projCF.InternalName] = "Moises was here";

            // Change task custom field value

            /*
             * --------------------------Important!---------------------------
             * if it is a lookup table customfield, need to be set as an array
             */
            task[taskCF.InternalName] = new[] { taskLookUpEntry.InternalName };

            // Change resource and assignment custom field value
            resource[resCF.InternalName]   = "Resource custom field value";
            assignment[resCF.InternalName] = "Assignment custom field value";

            // Update project and check in
            draft.Update();
            csom.JobState jobState = context.WaitForQueue(draft.Publish(true), DEFAULTTIMEOUTSECONDS);
            JobStateLog(jobState, "Updating project customfield values");
        }