在分组LINQ的（多个字段） [英] Grouping in Linq ( on multiple fields)

问题描述

我的分组使用LINQ的一些数据如下：

I am grouping some data using linq as following :

var groupedData = from row in salesTable.AsEnumerable()                   
group row by   
row.Field<string>("InvoiceNum") into grp
select grp;

我要重整旗鼓 groupedData 使用例如 row.Field（InvoiceNum），row.Field（InvoiceLineNum）某些领域，我不知道怎么做的LINQ分组与多个领域？

I want to regroup groupedData using some fields like row.Field("InvoiceNum") , row.Field("InvoiceLineNum") , I dont know how does the linq grouping works with multiple fields ?

推荐答案

使用一个匿名类型的对象分组。

Use an anonymously typed object for the grouping.

 var groupedData = from row in salesTable.AsEnumerable()                   
                   group row by new
                   {
                        InvoiceNum = row.Field<string>("InvoiceNum"),
                        InvoiceLineNum = row.Field<string>("InvoiceLineNum")
                   }
                   into grp
                   select grp;

或使用类名为

or using a named class

public class InvoiceGrouping : IEquatable<InvoiceGrouping>
{
     public string InvoiceNum { get; set; }
     public string InvoiceLineNum { get; set; }

     public bool Equals( InvoiceGrouping other )
     {
         return other != null 
                && this.InvoiceNum == other.InvoiceNum
                && this.InvoiceLineNum == other.InvoiceLineNum;
     }

     public override bool Equals( object other )
     {
         return Equals( other as InvoiceGrouping );
     }

     public override int GetHashCode()
     {
         unchecked
         {
            int hash = 17;
            hash *= (this.InvoiceNum != null ? 23 + this.InvoiceNum.GetHashCode() : 1);
            hash *= (this.InvoiceLineNum != null ? 23 + this.InvoiceLineNum.GetHashCode() : 1 );
            return hash;
         }
     }
 }

 var groupedData = from row in salesTable.AsEnumerable()                   
                   group row by new InvoiceGrouping
                   {
                        InvoiceNum = row.Field<string>("InvoiceNum"),
                        InvoiceLineNum = row.Field<string>("InvoiceLineNum")
                   }
                   into grp
                   select grp;

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