private string GetNextConstraintId(ContraintGroups group)
        {
            string abbr = Properties.Resources.ResourceManager.GetString(group.ToString()).ToUpper()[0].ToString();
            string first = abbr + "1";
            if (Constraints == null || Constraints.Count == 0)
                return first;
            int? n = Constraints.Where(c => c.ConstraintGroup==(short)group).Count();
            if(!n.HasValue)
                return first;

            return abbr + (n + 1);
        }
 private void AddConstraint(string constraintText, ContraintGroups group, double factor)
 {
     ProjectConstraint constraint = new ProjectConstraint() {
         ConstraintUId = System.Guid.NewGuid().ToString(),
         ProjectUId = Project.ProjectUId,
         Constraint = constraintText,
         AdjustPointFactor = factor,
         ConstraintGroup = (short) group,
         ConstraintId = GetNextConstraintId(group)
     };
     executor.StartBackgroundTask(
         () => { constraintsService.AddProjectConstraint(Project.ProjectUId, constraint); },
         () => {
             Constraints.Add(constraint);
             NewConstraint = "";
         });
 }