过滤一列数据的重复项，但显示另一列的所有数据

Question

我正在做 mvc3 和 linQ 我有这样的数据库，

class    student        gender

A        john           Male
B        George         Male
A        bill           Female
A        Steve          Male

我该如何编码来过滤重复项，结果如下

A
John       male
bill       female
steve      male

B
George     male

我尝试了方法A

  var bb = from bbb in unitOfWork.Checklists
                     orderby bbb.class
                     select bbb;

和方法B

        var group = (from p in unitOfWork.Checklists
                     group p by p.class into g
                     select new Checklists
                     {
                         class= g.Key,
                          name= g.ToString()
                     }).AsEnumerable();

，但都失败了~ 有什么想法吗？这让我很头疼！

Answer 1

尝试在 Visual Studio C# 示例中使用 ObjectDumper 项目

using System;
using System.Collections.Generic;
using System.Linq;

namespace testLinq
{
    public class Record
    {
        public string ClassName {get;set;}
        public string Student {get;set;}
        public string Gender {get;set;}


    }

    class Program
    {
        public static void Main(string[] args)
        {
            Console.WriteLine("Hello World!");

            Record[] list = new Record[] { 
                new Record { ClassName="A" , Student="john" , Gender="male" },
                new Record { ClassName="B" , Student="George" , Gender="male" },
                new Record { ClassName="A" , Student="bill" , Gender="Female" },
                new Record { ClassName="A" , Student="Steve" , Gender="male" }
            };

            var result = list.GroupBy(x => x.ClassName).Select(x => new { k = x.Key, person = x});

            ObjectDumper.Write(result, 1);

            Console.Write("Press any key to continue . . . ");
            Console.ReadKey(true);
        }
    }
}

输出是

Hello World!
k=A     person=...
  person: ClassName=A     Student=john    Gender=male
  person: ClassName=A     Student=bill    Gender=Female
  person: ClassName=A     Student=Steve   Gender=male
k=B     person=...
  person: ClassName=B     Student=George  Gender=male
Press any key to continue . . .

示例 MVC 代码

public class YourViewModel
{
    public YourViewModel()
    {
        Record[] list = new Record[] { 
            new Record { ClassName="A" , Student="john" , Gender="male" },
            new Record { ClassName="B" , Student="George" , Gender="male" },
            new Record { ClassName="A" , Student="bill" , Gender="Female" },
            new Record { ClassName="A" , Student="Steve" , Gender="male" }
        };

        var result = list.GroupBy(x => x.ClassName).Select(x => new { k = x.Key, person = x});
        using (var writer = new StringWriter())
        {
            ObjectDumper.Write(result, 1 , writer);
            pivotString = writer.ToString();
        }
    }

    private string pivotString;

    public string PivotTableText { get { return pivotString; } }
}

public static class YourHtmlExtension
{
    public static string EncodedMultiLineText(this HtmlHelper helper, string text) 
    {
      if (String.IsNullOrEmpty(text)) 
      {
        return String.Empty;
      }
      return Regex.Replace(helper.Encode(text), Environment.NewLine, "<br/>")
    }
}

在您的控制器中

    public ActionResult ReadPivotTable()
    {
        return View((new YourViewModel());
    }

在您的视图中

<%= Html.EncodedMultiLineText(Model.PivotTableText) %>

Answer 2

class 是 C# 中的关键字，不能用作属性名称。您需要一个分组依据，并且可能需要创建一个包装类来传递结果

from p in unitOfWork.Checklists
group p by p.Class into groupByClass
select new
{
   Class= groupByClass.Key,
   Students = groupByClass
}