c# - 在 C# 列表中如何选择所有列+几个自定义列，以便在每一行中所有列都是扁平的(不是嵌套的)？

Question

我有一个简单的 List，它的每一行都有 50 列。我想返回所有 50 列 + 3 个自定义列 但我想让列表的每一行都像一个平面(非嵌套)对象。

示例:

var newList = list.Select(x => new 
    {  x,
       d.CustomColA = x.ColA+10,
       d.CustomColB = x.ColB+30,
       d.CustomColC = x.ColC+50
    });

结果:它运行良好但每个结果行就像一个嵌套对象:

var row = newList.FirstOrDefault();
row.x.ColA
row.x.ColB
row.x.ColC
.....
row.CustomColA 
row.CustomColB 
row.CustomColB 

预期结果:

var row = newList.FirstOrDefault();
row.ColA
row.ColB
row.ColC
.....
row.CustomColA 
row.CustomColB 
row.CustomColB 

---

我使用了dynamic 类型并编写了以下代码，但它没有返回预期的结果:

var newList = list.Select(x =>
{
   dynamic d = x;
   d.CustomColA = x.ColA+10;
   d.CustomColB = x.ColB+30;
   d.CustomColC = x.ColC+50;
   return d;
   //return x;
});

监视面板中的结果:'newList.FirstOrDefault()' 引发了类型为 'Microsoft.CSharp.RuntimeBinder.RuntimeBinderException' 的异常

---

更新:

Attention: I wrote in my question that i have 50 columns and wrote anexample to show you i do not want name all the columns in the Select!(I know I can write name of all 53 column in a Select!) So that is not the correct answer.

Attention2: In the real project i have complicated custom columns but i wrote very simple example here to show what i want. Please write your flexible answers. Thank you.

Answer 1

所以您要做的基本上是映射一组属性。有用于此类事情的库，Automapper 是一个很好的库。但是，您也可以使用继承类中的反射构造函数自己完成此操作。看起来像这样:

假设:

• 你的类有 50 列，叫做 Cols
• 你可以继承Cols

public class CustomColumns : Cols
{
    public int CustomColA { 
        get{
            return this.ColA + 10;
        }
    }
    public int CustomColB { 
        get{
            return this.ColB + 30;
        }
    }
    public int CustomColC { 
        get{
            return this.ColC + 50;
        }
    }
    public CustomColumns(Cols cols)
    {
        string[] localNames = this.GetType().GetMembers().Where(m => m.MemberType == MemberTypes.Property).Select(m => m.Name).ToArray();
        string[] ctorNames = cols.GetType().GetMembers().Where(m => m.MemberType == MemberTypes.Property).Select(m => m.Name).ToArray();
        string[] names = localNames.Intersect(ctorNames).ToArray();
        foreach (string s in names)
        {
            PropertyInfo propSet = this.GetType().GetProperty(s);
            PropertyInfo propGet = typeof(Cols).GetProperty(s);
            propSet.SetValue(this, propGet.GetValue(cols, null));
        }
    }
}

这是在 dotnetfiddle 中工作的演示:https://dotnetfiddle.net/AKPYQD