c# - c# lambda linq 按多列索引排序

Question

我有一个查询，只想按以下顺序订购：ticketStatus = 先参加，然后是问题，然后是未付款，然后是已取消。谢谢

var duplicate = dt.AsEnumerable()
            .OrderBy((x,index) => index(ticketStatusOrder.IndexOf(x["TicketStatus"].ToString())))
            //.OrderBy(x => x["TicketStatus"].ToString() == "Attended")
            //.ThenBy(x => x["TicketStatus"].ToString() == "Issued")
            //.ThenBy(x => x["TicketStatus"].ToString() == "Unpaid")
            //.ThenBy(x => x["TicketStatus"].ToString() == "Cancelled")
            .GroupBy(x => new {EventID = x["EventID"].ToString(), ContactID = x["ContactID"].ToString()})
            .Select(x => x.FirstOrDefault()).CopyToDataTable();

标签： c#linqlambda

Answer 1

正如@mjwills 回答所建议的，创建一个枚举。但！

您无法对数据表进行就地排序，请参阅此答案。

因此，请按照以下两个步骤对数据表进行排序。

1. 创建一个枚举

   枚举 TicketStatuses { 已参加 = 1，已签发 = 2，未付 = 3，已取消 = 4 }

2. 我在 VS2017 和 .Net Core 2 中尝试了以下代码，并根据您的要求正确排序。

   class Program
   {
       static void Main(string[] args)
       {
           DataTable dt = new DataTable();
           DataColumn dc = new DataColumn("id", typeof(String));
           dt.Columns.Add(dc);
   
           dc = new DataColumn("TicketStatus", typeof(TicketStatuses));
           dt.Columns.Add(dc);
   
           DataRow dr;
           //Adding test data of 6 rows
           for (int i = 0; i <= 6; i++)
           {
               dr = dt.NewRow();
   
               dr[0] = i + 2; //Just a random column value - Could be anything here.
               dt.Rows.Add(dr);
           }
           // Setting column values for Column "TicketStatus" of our choice.
           dt.Rows[0][1] = TicketStatuses.Unpaid;
           dt.Rows[1][1] = TicketStatuses.Cancelled;
           dt.Rows[2][1] = TicketStatuses.Cancelled;
           dt.Rows[3][1] = TicketStatuses.Issued;
           dt.Rows[4][1] = TicketStatuses.Attended;
           dt.Rows[5][1] = TicketStatuses.Attended;
           dt.Rows[6][1] = TicketStatuses.Issued;
   
           //sorting datarows
           DataRow[] dataRows = dt.Select().OrderBy(u => u["TicketStatus"]).ToArray();
   
           DataTable sortedDatatable = dataRows.CopyToDataTable();
       }
   }
   

干杯!