C#LINQ:动态创建属性和值，其中包括来自分组查询的值的总和 [英] C# LINQ : Dynamically create property and values that includes sum of a value from a grouped query

问题描述

我的标题有点令人困惑，因此我将在这里进行解释.

My Title is slightly confusing so I will explain it here.

这是我的示例查询以及我希望实现的目标:

This is my sample query and what I wish to achieve:

var results = from row in toSearch.AsEnumerable()
              group by row.Field<String>("Somename") into grp
              select new
                        {
                         GroupMe = grp.Key,

                         foreach (var k in someDic.Keys){
                               TODOPROPERTYNAMEFROMk = grp.sum(x => grp.k);
                         }
                          };

这是我想要实现的一般想法.基于键的字典，我想从中创建属性名称，同时汇总分组查询中的数据.总和将基于键的值.
toSearch是一个数据表，字典的所有键构成该数据表的某些标头.在我看来，这似乎是不可能的，我已经搜索了一些资源，其中一个(我很抱歉失去了作者……)给了我这个解决方案:

This is the general idea of what I want to achieve. Based on a dictionary of keys, I want to create property names from it while summing up the data from the grouped query. The sum will be based off the value of the keys.
toSearch is a datatable and all of the keys of the dictionary makes up some of the headers of the datatable. This to me seems impossible and I have searched up a few sources and one of it (I lost the author sorry....) gave me this solution:

//For generating dynamic objects fr
  public static object DynamicProjection(object input, IEnumerable<string> properties)
{
    var type = input.GetType();
    dynamic dObject = new System.Dynamic.ExpandoObject();
    var dDict = dObject as IDictionary<string, object>;

    foreach (var p in properties)
    {
        var field = type.GetField(p);
        if (field != null)
            dDict[p] = field.GetValue(input);

        var prop = type.GetProperty(p);
        if (prop != null && prop.GetIndexParameters().Length == 0)
            dDict[p] = prop.GetValue(input, null);
    }

    return dObject;
}

我试图这样使用它

var results = from row in toSearch.AsEnumerable()
          group by row.Field<String>("Somename") into grp
          select grp;
var test = results.Select( x => DynamicProjection(x,someDic.Keys));

这给了我一个我无法利用或至少无法调用属性的对象.我真的很感激能帮助我实现最初的追求，并为长期的工作感到抱歉.

This gave me an object which i could not utilise or at least call properties out from. I would really appreciate any help in achieving what i was originally after and sorry for the long post.

编辑 预期的输入是一个数据表，例如:

Edit Expected input is a datatable eg:

Fee | Fi | Fo | Fum
cat | ds | 2  | 93
cow | ff | 5  | 120
cat | ds | 9  | 33
cow | jk | 1  | 133

按标题分组:费用
收到的标题:Fo，Fum
预期输出:

Group by header: Fee
Headers Received: Fo, Fum
Expected output:

cat | 11  | 126
cow | 6   | 253

优胜者:母牛，所以养牛*开个玩笑哈哈

Winner: Cow , so adopt a cow *Just joking lol

推荐答案

我对ExpandoObject不太熟悉(我的说法可能有误)，您可以使用Dictionary<columnname, sum>.

I'm not quite familiar with ExpandoObject (my arguments may wrong), you could work with Dictionary<columnname, sum>.

我建议返回带有标题和各自总和的Dictionary.

I would suggest return a Dictionary with the headers and respective sum.

// ex -- Given following header
List<string> headers = new List<string>();
headers.Add("fo");
headers.Add("fum");    

DataTable dt; // Assign correct data source.
var results =dt.AsEnumerable()
        .GroupBy(g=>g.Field<string>("fee"))       
        .Select(x=> new 
                {
                    x.Key, 
                    dict = headers.ToDictionary(h=>h, h=>x.Sum(s=>s.Field<int>(h)))
                })
        .ToList();  

此查询在fee列上分组，并计算给定标题列的总和.

This query groups on fee column and calculates sum for a given header columns.

选中此 Demo

输出:

Key=cat, column fo , Sum 11, column fum , Sum 126
Key=cow, column fo , Sum 6, column fum , Sum 253

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