C#Linq按包含特定值的子串列過濾串列-有解無憂

我正在嘗試選擇 item.itemApplications 串列包含 itemApplication.itemApplicationId == 5 的專案串列。尋找最簡單最干凈的方法來回傳串列<專案>。

{
"items": [
    {
        "itemId" : 1, 
        "itemApplications": [
            {
                "itemApplicationId": 7,
                "name": "application7",
            },
            {
                "itemApplicationId": 4,
                "name": "application4",
            }
        ]
    },
    {
        "itemId" : 2, 
        "itemApplications": [
            {
                "itemApplicationId": 3,
                "name": "application3",
            },
            {
                "itemApplicationId": 5,
                "name": "application5",
            }
        ]
    }
]

}

希望過濾只回傳 List < item >：

{
        "itemId" : 2, 
        "itemApplications": [
            {
                "itemApplicationId": 3,
                "name": "application3",
            },
            {
                "itemApplicationId": 5,
                "name": "application5",
            }
        ]
    }

uj5u.com熱心網友回復：

一種選擇是使用LinqwithWhere和Anyselect itemsWhere itemApplications.Any有一個itemApplicationId等于任何東西，在你的例子中，5：

public class Item
{
    public int itemId {get; set;}
    public List<ItemApplications> itemApplications { get; set; }
}

public class ItemApplications
{
    public int itemApplicationId {get; set;}
    public string name {get; set;}
}

List<Item> items = new List<Item>
{
    new Item { itemId = 1, itemApplications = new List<ItemApplications> { new ItemApplications { itemApplicationId = 7, name = "application7" }, new ItemApplications {  itemApplicationId = 4, name = "application4" } } },
    new Item { itemId = 2, itemApplications = new List<ItemApplications> { new ItemApplications {  itemApplicationId = 3, name = "application3" }, new ItemApplications {  itemApplicationId = 5, name = "application5" } } },
};

var i = items
            .Where(a => a.itemApplications
            .Any(b => b.itemApplicationId == 5))
            .ToList();

 i.ForEach(a => a.itemApplications
  .ForEach(b => Console.WriteLine($"id: {b.itemApplicationId}, name: {b.name}")));

//Prints
//id: 3, name: application3
//id: 5, name: application5

uj5u.com熱心網友回復：

你可以通過簡單地寫這個得到結果

  var desiredItems = (
                       from item in items
                       where item.itemApplications.Any(i => i.itemApplicationId == 5)
                       select item
                     ).ToList();

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標籤：C＃林克

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