c# - 使用 Linq 在两个嵌套 List 中透视数据

Question

我有以下类结构:

class Employee()
{
  public String Name { get; set; }
  public List<WorkDay> WorkDays { get; set; }
}

class WorkDay()
{
  public DateTime Date { get; set; }
  public Int Hours { get; set; }
}

是否可以旋转 List<Employee>使用 Linq，所以我的 DataGridView 中有这样的结果:

           | Name    | Name    |...| Name      |
Date       | Hours   | Hours   |   | Hours     |
Date       | Hours   | Hours   |   | Hours     |   
Date       | Hours   | Hours   |   | Hours     |
Date       | Hours   | Hours   |   | Hours     |
...        | Hours   | Hours   |   | Hours     |

这很棘手，因为它是两个嵌套列表，而且我只找到了非常简单的单个列表示例。 Is it possible to Pivot data using LINQ?

我已经到了这一步，但还没有到:

var _result = Employees.SelectMany(x => x.WorkDays)
                       .GroupBy(x => x.Date)
                       .Select(y => new
                                    {
                                        DATE = y.Key,
                                        NAME = y.Select(z => z.Employee.Name).ToArray()
                                    })
                       .ToList();

如果有任何建议，我将不胜感激。

Answer 1

我想你需要这个:-

var result = employees.SelectMany(x => x.WorkDays, (employeeObj, workDays) => 
                                                   new { employeeObj, workDays })
                      .GroupBy(x => x.workDays.Date)
                      .Select(x => new
                             {
                                Date = x.Key,
                                NameAndHours = x.Select(z => 
                                    new { 
                                            Name = z.employeeObj.Name, 
                                            Hours = z.workDays.Hours 
                                        })
                             }).ToList();

这是 Working Fiddle带有一些示例数据。