c# - 将 Let 与 LINQ 结合使用时如何避免重新创建对象

Question

这是我的数据:

private List<Department> Data
{
    get
    {
        return new List<Department>
        {
            new Department{
                Id = 1, 
                Name = "Tech",
                Employees = new List<Employee>{
                    new Employee{Name = "x", Id = 1 },
                    new Employee{ Name = "y", Id = 2}
                }
            },
            new Department{
                Id = 2,
                Name = "Sales",
                Employees = new List<Employee>{
                    new Employee{Name = "a", Id = 3},
                    new Employee {Name = "b", Id = 4}
                }
            }
        };
    }
}

在这里，我得到了所有员工及其相应部门的列表:

List<Employee> employees = (from department in Departments
                       let d = department
                       from e in d.Employees
                       select new Employee{
                            Id = e.Id,
                            Name = e.Name
                            Department = d
                       }).ToList();

令我困扰的是，我必须重新创建我的 Employee 对象才能将适当的部门附加到它。有没有一种方法可以在不必重新创建 Employee 的情况下编写 LINQ 语句？

可能有更好的方式来表达这个问题——如果有的话请随时告诉我。

编辑我走这条路的原因是我通过序列化我的部门来存储我的数据:

[
    {
        "Id":1,
        "Name":"Sales",
        "Employees":[{"Id":2,"Name":"x"},{"Id":1,"Name":"y"}]
    },
    {
        "Id":2,
        "Name":"Tech",
        "Employees":[{"Id":3,"Name":"d"},{"Id":4,"Name":"f"}]
    }

]

Answer 1

看起来您想使用 LINQ 来更新实例。这不是预期用途。使用 LINQ 查询您想要拥有的实例，然后循环更新结果。 (非嵌套)循环不是邪恶的。

var query = 
  from d in Departments
  from e in d.Employees
  select new { Employee = e, Department = d };

foreach(var x in query)
{
  x.Employee.Department = x.Department;
}