从自定义列表对象中删除重复项 [重复项]

Question

总结：从自定义列表列表中删除重复项

我尝试使用各种现有方法从其他堆栈溢出帖子中删除重复项，一些示例是：

var distinctWords = combinedList.Distinct().ToList();

fooArray.GroupBy(x => x.Id).Select(x => x.First());

这些解决方案仅根据 1 个条件进行过滤，我需要根据 2 个条件删除重复项，如果年份和 id 匹配，则需要删除重复项。可以有不同的年份具有相同的 id。我想在不使用 MoreLINQ 的情况下执行此操作。

型号：

    public class data
    {
        public List<Inventory> inventory { get; set; }
        public List<LocationInventory> locationinventory { get; set; }

    }

    public class Inventory
    {
        public string name{ get; set; }
        public string year{ get; set; }
        public string id{ get; set; }
    }

    public class LocationInventory
    {
        public string location { get; set; }
        public List<Inventory> inventory { get; set; }
    }

控制器：

        public ActionResult getData(string[] Make, string[] Location)
        {
            data inv = new Models.data();

            //Make a list of the inventory lists
            inv.locationinventory = new List<LocationInventory>();

            //Split the Manufacturer and Location at the commas and store in new array
            string[] Make_Values = Make[0].Split(',');
            string[] Location_Values = Location[0].Split(',');

            //Get values for the tables
            var popData = new List<Inventory>();

            foreach (var Location_Value in Location_Values)
            {
                //Populate the data for each location
                //populateData returns a List<Inventory>
                popData = populateData(Make_Values, Location_Value.ToString());

                //Add the data to model with cooresponding location and inventory
                inv.locationinventory.Add(new LocationInventory{ location = Location_Value, inventory = popData });
            }

            return PartialView("Table", inv);
        }

查看：

@{
    var inventories = Model.locationinventory.Select(x => x.inventory).Distinct().ToList();
    var list1 = new List<Project1.Models.Inventory>();
    var list2 = new List<Project1.Models.Inventory>();

    foreach (var inv in inventories)
    {
        if (list1?.Any() != true)
        {
            list1 = inv;
        }

        if (list1?.Any() != false)
        {
            list2 = inv;
        }

        var combinedList = list1.Union(list2);

        var test = combinedList.GroupBy(x => new { x.id, x.year }).ToList();

        <div>
            <table>                
                @foreach (var l in test)
                {
                    foreach (var m in l)
                    {
                        <thead>
                            <tr>
                                <td>@m.name</td>
                                <td>@m.year</td>
                                <td>@m.id</td>
                            </tr>
                        </thead>
                    }
                }
            </table>
        </div>
    }

}

当前结果：

iphone 2019 x1234
iphone 2019 x1234
iphone 2020 x1234
iphone 2018 x1234
iwatch 2019 a4321
iwatch 2020 a4321
android 2020 n9876
android 2020 n9876
android 2019 n9876

预期结果：

iphone 2019 x1234
iphone 2020 x1234
iphone 2018 x1234
iwatch 2019 a4321
iwatch 2020 a4321
android 2020 n9876
android 2019 n9876

Answer 1

你有点接近你需要的东西，但并不完整。分组后，您只需从每个组中投影一行：

var uniqueInventory = combinedList.GroupBy(x => new { x.name,x.id, x.year })
                                  .Select(x => x.First())
                                  .ToList();

现在它将为每个组包含一个项目，并且所有项目都是唯一的条目。

另一种方法是实现IEqualityComparer，可以在Distinct方法中传递。

public class InventoryComparer: IEqualityComparer<Inventory>
{
    public override bool Equals(Inventory a, Inventory b)
    {
        return a.name == b.name
            && a.id == b.id
            && a.year == b.year;
    }

    public override int GetHashCode(Inventory inventory)
    {
        return inventory.id.GetHashCode();
    }
}

现在我们可以像这样使用它：

var uniqueInventory = combinedList.Distinct(new InventoryComparer());