c# Ef 表达式拼接

                var field = "mCurrentBalance";
                var propInfo = GetPropertyInfo(typeof(MsgOrders), field);
                var paramExpr = Expression.Parameter(typeof(MsgOrders));
                var propAccess = Expression.PropertyOrField(paramExpr, propInfo.Name);
                var expr = Expression.Lambda(propAccess, paramExpr);

                //var member = Expression.Property(paramExpr, propInfo);
                //var mList = new List<MemberBinding>();
                //mList.Add(Expression.Bind(propInfo, member));
                //var mm = Expression.MemberInit(Expression.New(typeof(MsgOrders)), mList.ToArray());

                var expression =
                    Expression.Lambda<Func<MsgOrders, object>>(expr, new ParameterExpression[] { paramExpr });