Question

所以这是一个困扰我好几个小时的设计问题，我必须联系小组寻求帮助。我有一个包含数千个共享实体的集合，需要从两个列表中包含的三个不同属性中检索不同的管理器列表，两个管理器位于Stores列表中，一个管理器来自仓库集合。

为了简化问题，我编写了一个简单的控制台程序，突出了挑战。我把它扔在一起，所以是的，我知道这是低效的，但它证明了问题：

    public class Program
    {
        static void Main(string[] args)
        {
            DistributionGroup d = new DistributionGroup();
            Console.WriteLine("====Store Managers====");
            foreach(Manager m in d.Stores.Select(m => m.StoreManager).Distinct())
            {
                Console.WriteLine("{0}:{1}", m.Id, m.Name);
            }

            Console.WriteLine("=====Inv. Managers=====");
            foreach (Manager m in d.Stores.Select(m => m.InventoryManager).Distinct())
            {
                Console.WriteLine("{0}:{1}", m.Id, m.Name);
            }

            Console.WriteLine("===Warehouse Managers===");
            foreach (Manager m in d.Warehouses.Select(m => m.WarehouseManager).Distinct())
            {
                Console.WriteLine("{0}:{1}", m.Id, m.Name);
            }                
        }
    }
    public class DistributionGroup
    {
        private Manager m1 = new Manager(1, "Bob Wilson");
        private Manager m2 = new Manager(2, "Chris Warren");
        private Manager m3 = new Manager(3, "Mike Olsen");
        private Manager m4 = new Manager(4, "Aaron Erikson");

        public List<RetailStore> Stores;
        public List<Warehouse> Warehouses;

        public DistributionGroup()
        {
            RetailStore s1 = new RetailStore(1, m1, m1);
            RetailStore s2 = new RetailStore(2, m1, m3);
            RetailStore s3 = new RetailStore(3, m2, m2);
            Warehouse w1 = new Warehouse(1, m4);
            Warehouse w2 = new Warehouse(2, m2);

            Stores = new List<RetailStore>();
            Stores.Add(s1);
            Stores.Add(s2);
            Stores.Add(s3);

            Warehouses = new List<Warehouse>();
            Warehouses.Add(w1);
            Warehouses.Add(w2);
        }
    }

    public class Manager
    {
        public int Id;
        public string Name;
        public Manager(int id, string name)
        {
            Id = id; Name = name;
        }
    }
    public class RetailStore
    {
        public int Id;
        public Manager StoreManager;
        public Manager InventoryManager;
        public RetailStore(int id, Manager mgr, Manager inventoryMgr)
        {
            Id = id;
            StoreManager = mgr;
            InventoryManager = inventoryMgr;
        }
    }

    public class Warehouse
    {
        public int Id;
        public Manager WarehouseManager;
        public Warehouse(int id, Manager mgr)
        {
            Id = id;
            WarehouseManager = mgr;
        }
    }

我需要做的是从所有三个属性生成一个独特的Managers列表：

RetailStore.StoreManager
RetailStore.InventoryManager
Warehouse.WarehouseManager

因此，按照示例，控制台输出将只是：

1：Bob Wilson   2：Chris Warren
  3：Mike Olsen
  4：Aaron Erikson

我一直在努力弄清楚语法，但LINQ不是一种力量，我希望这个小组可以帮助我。

Answer 1

好像你需要使用Enumerable.Union

var allManagers = d.Stores.Select(m => m.StoreManager).Union(d.Stores.Select(m => m.InventoryManager))
                                                      .Union(d.Warehouses.Select(m => m.WarehouseManager));
foreach (Manager m in allManagers)
{
    Console.WriteLine("{0}:{1}", m.Id, m.Name);
}

请注意，Union会返回输入序列中的唯一值，因此无需调用Distinct。

如何：从具有1个或多个相同类型属性的多个列表<t>中选择不同的对象<t>

1 个答案: