C＃如何找到特定項目，並將其從名單

Question

相關的項目我有下面的類

public class Item 
{ 
    public int Id { get; set; } 
    public int ParentId { get; set; } 
    public string Content { get; set; } 
    public bool IsLastItem { get; set; } 
} 

讓說，我有以下的模型，我想找到標識特定項目和它的相關項目的ID。在這種情況下，我想查找item9的Id，它是相關的項目ID。

結果應該包含9，10，11，12，13，14

我從數據庫中獲得我的模型的列表，我模擬它的代碼塊這樣

var items = new List<Item> 
{ 
    new Item 
    { 
     Id = 1, 
     ParentId = 0, 
     Content = "item1", 
     IsLastItem = false 
    }, 
    new Item 
    { 
     Id = 2, 
     ParentId = 1, 
     Content = "item2", 
     IsLastItem = false 
    }, 
    new Item 
    { 
     Id = 3, 
     ParentId = 1, 
     Content = "item3", 
     IsLastItem = true 
    }, 
    new Item 
    { 
     Id = 4, 
     ParentId = 1, 
     Content = "item4", 
     IsLastItem = true 
    }, 
    new Item 
    { 
     Id = 5, 
     ParentId = 2, 
     Content = "item5", 
     IsLastItem = false 
    }, 
    new Item 
    { 
     Id = 6, 
     ParentId = 5, 
     Content = "item6", 
     IsLastItem = false 
    }, 
    new Item 
    { 
     Id = 7, 
     ParentId = 5, 
     Content = "item7", 
     IsLastItem = false 
    }, 
    new Item 
    { 
     Id = 8, 
     ParentId = 6, 
     Content = "item8", 
     IsLastItem = true 
    }, 
    new Item 
    { 
     Id = 9, 
     ParentId = 7, 
     Content = "item9", 
     IsLastItem = false 
    }, 
    new Item 
    { 
     Id = 10, 
     ParentId = 9, 
     Content = "item10", 
     IsLastItem = true 
    }, 
    new Item 
    { 
     Id = 11, 
     ParentId = 9, 
     Content = "item11", 
     IsLastItem = false 
    }, 
    new Item 
    { 
     Id = 12, 
     ParentId = 11, 
     Content = "item12", 
     IsLastItem = true 
    }, 
    new Item 
    { 
     Id = 13, 
     ParentId = 11, 
     Content = "item13", 
     IsLastItem = true 
    }, 
    new Item 
    { 
     Id = 14, 
     ParentId = 11, 
     Content = "item14", 
     IsLastItem = true 
    } 
}; 

Answer 1

你需要一個遞歸的方法

// Start finding the base item to start the recursive search 
Item x = items.Where(i => i.Id == 9).FirstOrDefault(); 
List<Item> found = Search(items, x); 

// Insert the starting item at the first position (Add is also good but...) 
found.Insert(0, x); 



public List<Item> Search(List<Item> list, Item parent) 
{ 
    // Prepare the list to return... 
    List<Item> found = new List<Item>(); 
    if (parent != null) 
    { 
     // Search all the items that have the parent passed 
     List<Item> temp = list.Where(x => x.ParentId == parent.Id).ToList(); 
     // Add the list to the return variable 
     found.AddRange(temp); 
     // For each child of this parent look for their childs 
     foreach(Item x in temp) 
      found.AddRange(Search(list, x)); 
    } 
    return found; 
} 

Answer 2

您可以使用LINQ，類似下面應該讓你開始...

var parent = items.First(x => x.Content == "item9"); 
var children = items.Where(x => x.Id == parent.Id);