[英]How to recursively get all the parents from a child c#?
有所有視圖位置(比如說 100,這些是 TreeView 的位置):Id、Name、ParentId 1 Root Null 2 Semi-root 1 3 Semi-semi-root 2 4.....
還有一些數據,我們只從另一個請求中收到與我們的值相對應的位置:Id、Name、ParentId 22 Location1 12 36 Location38 21 99 Location38 3
需要獲取我們從請求中獲得的數據的所有父層次結構。 有 class:
public class TreeViewNode {
public Guid Id {get; set;}
public string Name {get; set;}
public Guid ParentId {get; set;}
}
測試數據:
private IEnumerable<TreeViewNode> SeedData()
{
return new List<TreeViewNode>
{
new()
{
Id = 1,
Name = "Root",
ParentId = null
},
new()
{
Id = 2,
Name = "Semi-root",
ParentId = 1
},
new()
{
Id = 3,
Name = "Semi te",
ParentId = 2
},
new()
{
Id = 4,
Name = "Semi oi",
ParentId = 2
},
new()
{
Id = 5,
Name = "Child",
ParentId = 3
},
new()
{
Id = 6,
Name = "Child 1",
ParentId = 4
},
new()
{
Id = 7,
Name = "Child 2",
ParentId = 1
},
new()
{
Id = 8,
Name = "Child 3",
ParentId = 1
},
new()
{
Id = 9,
Name = "Child 4",
ParentId = 1
},
new()
{
Id = 10,
Name = "Child 6",
ParentId = 2
}
};
}
從請求中獲得的示例數據:
var dataFromRequest = new List<TreeViewNode>
{
new()
{
Id = 8,
Name = "Child 3",
ParentId = 1
},
new()
{
Id = 10,
Name = "Child 6",
ParentId = 2
},
new()
{
Id = 33,
Name = "Child",
ParentId = 3
},
new()
{
Id = 4,
Name = "Semi oi",
ParentId = 2
}
};
結果需要得到這樣的父母名單:
Id Name ParentId
1 Root Null
2 Semi-root 1
3 Semi te 2
這里可以是5個或更多級別的父母
像這樣的東西
// create Dictionary for lookups
var lookup = dataFromRequest.ToDictionary(x => x.Id.Value, x => x);
var lookFor = new TreeViewNode()
{
Id = 6,
Name = "Child 1",
ParentId = 4
};
// get all the parents
GetParents(lookup, lookFor);
獲取所有父母的幫助方法
private void GetParents(Dictionary<int, TreeViewNode> lookup,
TreeViewNode lookFor)
{
while (lookFor != null)
{
// Alternative: Add lookFor to List<TreeViewNode> here and return at
// the end of the method
Debug.WriteLine($"{lookFor.Id} {lookFor.Name} {lookFor.ParentId}");
if (lookFor.ParentId == null)
break;
// cast ParentId to corrent dataType here Guid or int
lookup.TryGetValue((int)lookFor.ParentId, out var parentNode);
lookFor = parentNode;
}
}
當您獲得更多IEnumerable<TreeViewNode>
時,請記住讓您的查找字典保持最新
您可以做的另一件事是在TreeViewNode
中設置父節點,如下所示:
public class TreeViewNode {
...
// set ParentNode by lookup in the Dictionary once
public TreeViewNode ParentNode {get; set;}
}
聲明:本站的技術帖子網頁,遵循CC BY-SA 4.0協議,如果您需要轉載,請注明本站網址或者原文地址。任何問題請咨詢:yoyou2525@163.com.