public Response <Messages.Label> AddLabel(Messages.Label label)
        {
            using (Entities db = new Entities())
            {
                if (db.Label.FirstOrDefault(m => m.Name == label.Name) != null)
                {
                    return new ErrorResponse <Messages.Label>()
                           {
                               ErrorCode = ErrorCode.NameAlreadyInUse
                           }
                }
                ;

                var added = db.Label.Add(new Models.Label()
                {
                    Name = label.Name
                });

                db.SaveChanges();

                return(new Response <Messages.Label>()
                {
                    Data = new Messages.Label()
                    {
                        Id = added.Id,
                        Name = added.Name
                    }
                });
            }
        }
        public Response <Messages.Label> AddLabelToDataSet(int?id, Messages.Label label)
        {
            if (id == null)
            {
                return new ErrorResponse <Messages.Label>()
                       {
                           ErrorCode = ErrorCode.InvalidId
                       }
            }
            ;

            using (Entities db = new Entities())
            {
                var dataSet = db.DataSet.FirstOrDefault(d => d.Id == id);

                if (dataSet == null)
                {
                    return new ErrorResponse <Messages.Label>()
                           {
                               ErrorCode = ErrorCode.DataSetNotFound
                           }
                }
                ;

                dataSet.Mapping.Add(new Mapping()
                {
                    LabelId = label.Id
                });

                db.SaveChanges();

                return(new Response <Messages.Label>()
                {
                    Data = new Messages.Label()
                    {
                        Id = label.Id,
                        Name = label.Name
                    }
                });
            }
        }