如何在 C# dotnet 中将 HierarchyId 转换为 Child/Parent (Tree) 结构？

Question

出于性能等原因，我必须在我的数据库中使用HiarachyId。我必须将 HierarchyId 数据类型转换为 JSON 才能显示在 FancyTree 中。

我使用解决方案here，但不起作用。我的代码是

static void Main(string[] args)
    {

        {

        var dd = new List<Field>();
        dd.Add(new Field(1, "Earth", HierarchyId.Parse("/")));
        dd.Add(new Field(2, "Europe", HierarchyId.Parse("/1/")));
        dd.Add(new Field(3, "South America", HierarchyId.Parse("/2/")));
        dd.Add(new Field(4, "Antarctica", HierarchyId.Parse("/3/")));
        dd.Add(new Field(5, "Brazil", HierarchyId.Parse("/2/1/")));
        dd.Add(new Field(6, "France", HierarchyId.Parse("/1/1/")));
        dd.Add(new Field(7, "Germany", HierarchyId.Parse("/1/4/")));
        dd.Add(new Field(8, "test", HierarchyId.Parse("/1/5/")));
        dd.Add(new Field(9, "McMurdo Station", HierarchyId.Parse("/3/1/")));
        dd.Add(new Field(10, "Italy", HierarchyId.Parse("/1/3/")));
        dd.Add(new Field(11, "Spain", HierarchyId.Parse("/1/2/")));
        dd.Add(new Field(12, "Morano", HierarchyId.Parse("/1/3/1/")));
        dd.Add(new Field(13, "Rio de Janeiro", HierarchyId.Parse("/2/1/3/")));
        dd.Add(new Field(14, "Paris", HierarchyId.Parse("/1/1/1/")));
        dd.Add(new Field(15, "Madrid", HierarchyId.Parse("/1/2/1/")));
        dd.Add(new Field(16, "Brasilia", HierarchyId.Parse("/2/1/1/")));
        dd.Add(new Field(17, "Bahia", HierarchyId.Parse("/2/1/2/")));
        dd.Add(new Field(18, "Salvador", HierarchyId.Parse("/2/1/2/1/")));
        dd.Add(new Field(19, "tets1", HierarchyId.Parse("/2/1/3/1/")));
        dd.Add(new Field(20, "test2", HierarchyId.Parse("/2/1/3/1/1/")));
        dd.Add(new Field(21, "test3", HierarchyId.Parse("/2/1/3/1/1/1/")));
        dd.Add(new Field(22, "test24", HierarchyId.Parse("/2/1/3/1/1/2/")));

            MyClass clss = new MyClass();
            var x=  clss.NewMthodTest(dd);

        }

    }

获取子方法：

     public class MyClass
{
    public List<HierarchicalNode> NewMthodTest(List<Field> query)
    {

        var root = new HierarchicalNode("Root", 0);
        foreach (var rec in query)
        {
            var current = root;
            foreach (string part in rec.Node.ToString().Split(new[] { '/' },
                                           StringSplitOptions.RemoveEmptyEntries))
            {
                int parsedPart = int.Parse(part);
                current = current.Children[parsedPart - 1];
            }
            current.Children.Add(new HierarchicalNode(rec.FieldName, rec.Id));
        }
        return null; // in this method i don't know what do we suppose to return 
    }
}

我的输入参数class是：

    public class Field 
    {
        public Field(long id, string fieldName, HierarchyId node)
        {
            Id = id;
            FieldName = fieldName;
            Node = node;
        }
        public long Id { get; set; }
        public string FieldName { get; set; }
        public HierarchyId Node { get; set; }
    }

并且输出 class 是

    class HierarchicalNode
{
    private readonly List<HierarchicalNode> children =
        new List<HierarchicalNode>();
    public List<HierarchicalNode> Children { get { return children; } }

    private readonly string name;
    public string Name { get { return name; } }

    private readonly long id;
    public long Id { get { return id; } }

    public HierarchicalNode(string name, long id)
    {
        this.name = name;
        this.id = id;
    }
}

似乎出了点问题，它 returns 是这样的：

Answer 1

网上找了很多无果，自己用c#的递归方法解决了

我把我的总代码放在这里是为了帮助以后搜索这个问题的人。如果有人有什么好的建议可以让它变得更好，请留言让我开心。

这是我的代码：

这是调用 GetTreeMethod 的 My Main 方法

  public List<TreeView> GetTree()
    {
       //get all nodes from DB to make a collection in RAM
        var nodesColect = _getFieldsList.GetFieldsByNode("/");

        var x = GetTreeMethod("/", nodesColect);

        return x;
    }

这是我主要的递归方法

private List<TreeView> GetTreeMethod(string nodeStr,List<FieldListDto> lstCollection)
    {
        List<TreeView> lst = new List<TreeView>();
        HierarchyId node = HierarchyId.Parse(nodeStr);
        var lastItemInCurrentLevel = GetChilds(node, lstCollection);

        foreach (var item in lastItemInCurrentLevel)
        {
            TreeView tr = new TreeView
            {
                title = item.title,
                id = item.id,
                node = item.node,
                fin = item.fin,
            };
            tr.children = GetTreeMethod(item.node.ToString(), lstCollection);
            lst.Add(tr);
        }

        return lst;
    }

这只会给出特定节点的子节点

   private List<TreeView> GetChilds(HierarchyId node, List<FieldListDto> lstCollection)
    {
        List<TreeView> child = lstCollection.Where(x => x.Node.ToString() != "/" && x.Node.GetAncestor(1).ToString() == node.ToString()).Select(q => new TreeView { id = q.Id, node = q.Node, title = q.FieldName }).ToList();
        return child;

    }

型号

public class FieldListDto  
{
    public long id { get; set; }
    public string FieldName { get; set; }
    public HierarchyId Node { get; set; }
}
 public class TreeView
{
    public long id { get; set; }
    public string title { get; set; }
    public HierarchyId node { get; set; }
    public List<TreeView> children { get; set; }
}

这里是我的 SQL 数据这是我的最终结果

Answer 2

使用 HierarchyId 的好处之一是您可以在不进行递归调用的情况下构建树。

我也会以不同的方式命名。假设您将数据库称为 table 个节点。这是 table 结构：

CREATE TABLE dbo.Nodes
(
       [NodeId]          [int]            NOT NULL,
       [NodeName]        [nvarchar](100)  NOT NULL,
       [HierarchyId]     [hierarchyid]    NOT NULL,
       [Level]       AS [HierarchyId].GetLevel() PERSISTED,
       CONSTRAINT Primary_Key_Nodes PRIMARY KEY CLUSTERED ([NodeId]) 
);

CREATE UNIQUE NONCLUSTERED INDEX
     [Nodes_1]
ON
[dbo].[Nodes] ([HierarchyId] ASC);

 
--Important - put level as the first column to index
CREATE UNIQUE NONCLUSTERED INDEX
    [Nodes_2]
ON
[dbo].[Nodes] ([Level] ASC, [HierarchyId] ASC);

这是给定父节点的 SQL 到 return 节点。我会将其包装在一个名为 GetDescendantsAndSelf():

的函数中

SELECT
      [NodeId]
      ,[NodeName]
      ,[HierarchyId].ToString() AS 'HierarchyPath'
FROM
      [dbo].[Nodes]
WHERE
      [HierarchyId].IsDescendantOf(@parentHierarchyId) = 1
ORDER BY
    [Level] ASC
    ,[NodeName] ASC;

我的数据传输对象可能如下所示：

public class TreeNode
{
   public string Text { get; set; } = String.Empty;
   public List<TreeNode> Nodes { get; set; } = new List<TreeNode>();
}

GetDescendantsAndSelf() 应该return 像这样的节点数据访问对象列表：

public class Node
{
    public int NodeId { get; set; }
    public string NodeName { get; set; } = String.Empty;
    public SqlHierarchyId HierarchyId { get; set; }
    public int Level => HierarchyId.GetLevel().ToSqlInt32().Value;
}

这里是构建树的代码：

TreeNode? rootNode = null;

Dictionary<string, TreeNode> treeBuilder = new Dictionary<string, TreeNode>();
string parentHierarchyId = "/1/2/3";
var nodes = GetDescendantsAndSelf(parentHierarchyId);
foreach (Node node in nodes)
{
    TreeNode currentNode = new TreeNode() { Text = node.NodeName };
    treeBuilder[node.HierarchyId.ToString()] = currentNode;

    if (node.Level == 1)
    {
        rootNode = currentNode;
    }
    else
    {
        string parentKey = node.HierarchyId.GetAncestor(1).ToString();
        treeBuilder[parentKey].Nodes.Add(currentNode);
    }
}

if (rootNode is {})
{
     //rootNode contains your tree structure
}
else
{
     //no data found for parentHierarchyId
}

如何在 C# dotnet 中将 HierarchyId 转换为 Child/Parent (Tree) 结构？

How to convert HierarchyId to Child/Parent (Tree) structure in C# dotnet?

c#

asp.net

.net-core

hierarchyid