Lambda 动态Select

问题:

我现在要实现Lambda动态添加Select字段，我贴出部分代码

             if (Field.ToLower().Contains("cod"))
                {
                    ret.Data = new
                    {
                        Total = Total,
                        Data = GetSelector(data, s => new { s.Id, s.N_StationId, s.N_JckId, s.ReportTime, s.COD_Avg, s.COD_Max, s.COD_Min }).ToList().Select((s, i) => new
                        {
                            Num = (Page - 1) * PageSize + 1 + i++,
                            s.Id,
                            s.N_StationId,
                            s.N_JckId,
                            s.ReportTime,
                            s.COD_Avg,
                            s.COD_Max,
                            s.COD_Min
                        })
                    };
                }



                if (Field.ToLower().Contains("ph"))
                {
                    ret.Data = new
                    {
                        Total = Total,
                        Data = GetSelector(data, s => new { s.Id, s.N_StationId, s.N_JckId, s.ReportTime, s.PH_Avg, s.PH_Max, s.PH_Min }).ToList().Select((s, i) => new
                        {
                            Num = (Page - 1) * PageSize + 1 + i++,
                            s.Id,
                            s.N_StationId,
                            s.N_JckId,
                            s.ReportTime,
                            s.PH_Avg,
                            s.PH_Max,
                            s.PH_Min
                        })
                    };
                }


          private IQueryable<T> GetSelector<T>(IQueryable<T_Report_Year> db, Expression<Func<T_Report_Year, T>> selector)
    {
        return db.Select(selector);
    }

这个代码实现的是只包含其中一个cod或ph时可以动态，那要多个同时包含，怎么改进这段代码呢？

回答1:

代码生成 Expression 。