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

For some reason such as performance, I have to use HiarachyId in my database. I have to convert the HierarchyId data type to JSON to show up in FancyTree.
I Use the solution here but won't work. My code was
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);
}
}
Method to get child:
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
}
}
and my input parameter class is :
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; }
}
and output class is
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;
}
}
it seems something wrong and it returns this:

One of the benefits of using HierarchyId is so that you can build a tree without doing recursive calls.
I would also name things a big differently. Let's say you call your database table Nodes. Here is the table structure:
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);
Here is the SQL to return nodes for a given parent. I would wrap this up in a function called GetDescendantsAndSelf():
SELECT
[NodeId]
,[NodeName]
,[HierarchyId].ToString() AS 'HierarchyPath'
FROM
[dbo].[Nodes]
WHERE
[HierarchyId].IsDescendantOf(#parentHierarchyId) = 1
ORDER BY
[Level] ASC
,[NodeName] ASC;
My data transfer object could look like this:
public class TreeNode
{
public string Text { get; set; } = String.Empty;
public List<TreeNode> Nodes { get; set; } = new List<TreeNode>();
}
GetDescendantsAndSelf() should return a list of Node data access objects like this one:
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;
}
Here is the code to build a tree:
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
}

After a lot of search On the net with no result, I solve this by myself with a recursive method in c#.
I put my total code here to help people who search in the future for this question. If someone has any nice advice to make it better please leave a note and make me happy.
This is my code:
This is My Main method which calls GetTreeMethod
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;
}
This is my main recursive method
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;
}
this just gives children of a specific node
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;
}
Models
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; }
}
here my SQL data
and here my final result

How would I search through all nested children of a custom class?

I have a table in a database which looks like this:
| id | parentID | name |
|----------+----------+-------------|
|ABCD-12345| | Top |
|----------+----------+-------------|
|ABCD-23456|ABCD-12345| Middle |
|----------+----------+-------------|
|ABCD-34567|ABCD-23456| Bottom |
|----------+----------+-------------|
|ABCD-45678|ABCD-23456| Bottom |
etc. - Basically, a hierarchical structure of N depth. I've taken this and shoved it into a datatable.
I have the following class built to hold this data:
public class TreeNode
{
public string id { get; set; }
public string name { get; set; }
public string parentID { get; set; }
public List<TreeNode> children { get; set; }
}
My goal is to go through each of these DataTable rows and insert them into the appropriate location in the TreeNode structure, but I'm super confused as to how I should approach this.
The main point of confusion for me is how I search through the entire existing structure of TreeNodes to see if a node with the parentID exists. Can anyone point me in the right direction?
I tried the following code, but it doesn't work:
public List<TreeNode> BuildTree(int currNode, List<TreeNode> treeList, DataTable dt)
{
foreach(DataRow row in dt.Rows)
{
if(row[1].ToString() == treeList[currNode].id)
{
treeList[currNode].children.Add(new TreeNode
{
id = row[0].ToString(),
name = row[2].ToString(),
parentID = row[1].ToString()
});
dt.Rows.Remove(row);
if(dt.Rows.Count > 0)
{
currNode++;
BuildTree(currNode, treeList, dt);
}
else
{
return treeList;
}
}
}
return null;
}
The problem is this line:
if(row[1].ToString() == treeList[currNode].id)
which gets an out of range exception, because I have a root at index 0, so on the second run (when currNode is 1), it breaks. I need to traverse to treeList[0].Children[int], followed by treeList[0].Children[int].Children[int] and so on and so forth.
So how do I accomplish this goal?

First I'm going to modify the TreeNode class for our convenience. It's not necessary, but just a nice to have. Also I'm going to assume that in your datatable you've done your error checking and there's only one node with ParentId = "".
public class TreeNode
{
public string Id { get; set; }
public string Name { get; set; }
public string ParentID { get; set; }
public List<TreeNode> Children { get; set; }
public TreeNode()
{
Id = Name = ParentID = string.Empty;
Children = new List<TreeNode>();
}
public bool IsRoot { get { return ParentID == string.Empty; } }
public bool IsChild { get { return Children == null || Children.Count == 0; } }
}
First, I'd convert your datatable data into a list of TreeNode objects. Forget about relationships, just create a list with each objects Children being empty. I wrote a method to simulate data retrival from datatable. Instead of that you can use your actual datatable.
static List<DataTableData> GetDataTableData()
{
var data = new List<DataTableData>
{
new DataTableData() { Id = "23456", ParentID = "12345", Name = "Middle" },
new DataTableData() { Id = "55555", ParentID = "12345", Name = "Middle" },
new DataTableData() { Id = "34567", ParentID = "23456", Name = "Bottom" },
new DataTableData() { Id = "12345", ParentID = string.Empty, Name = "Top" },
new DataTableData() { Id = "45678", ParentID = "23456", Name = "Bottom" },
new DataTableData() { Id = "66666", ParentID = "55555", Name = "Bottom" }
};
return data;
}
And this is what your Main() would look like:
static void Main(string[] args)
{
var treeNodes = new List<TreeNode>();
var dataTable = GetDataTableData();
foreach (var data in dataTable)
{
treeNodes.Add(new TreeNode() { Id = data.Id, Name = data.Name, ParentID = data.ParentID });
}
var root = BuildTree(treeNodes);
Console.ReadLine();
}
Now, in my BuildTree() method, instead of passing the datatable I can pass my TreeNode list, and return just the root node.
public static TreeNode BuildTree(List<TreeNode> nodes)
{
foreach (var node in nodes)
{
node.Children = nodes.Where(x => x.ParentID == node.Id).ToList();
}
return nodes.Find(x => x.IsRoot);
}
BuildTree() Breakdown
The nodes list already have all the nodes corresponding to data in your datatable. The BuildTree() is merely going to create the parent-child relations and fill in each object's Children list.
So I iterate through the list, and see what other elements in the list are supposed to be its children. When you have iterated through the list you'd created all the parent-child relationships. Finally, I pick the root node (the one who's ParentId is empty) and return it.
Edit
Here's an easy method to print and verify your tree.
static void PrintTree(TreeNode node, int indents)
{
for (int tab = 0; tab < indents; tab++)
{
Console.Write("\t");
}
Console.WriteLine("{0} - {1}", node.Id, node.Name);
if (node.Children != null && node.Children.Count > 0)
{
indents++;
foreach (var child in node.Children)
{
PrintTree(child, indents);
}
}
}
My output looks like this:

If you are building a class structure then you need a class with a recursive method. Not sure how efficient this will be if it gets too big. Execute the method from the top of the tree.
public class TreeNode
{
public string id { get; set; }
public string name { get; set; }
public string parentID { get; set; }
public List<TreeNode> children { get; set; }
public TreeNode() {
children = new List<TreeNode>();
}
public TreeNode FindParentWithID(string ID)
{
TreeNode ParentWithID = null;
//check my parentID if i am the one being looked for then return
if (id == ID) return this;
//search children
foreach (TreeNode treeNode in children)
{
ParentWithID = treeNode.FindParentWithID(ID);
if (ParentWithID != null)
{
break;
}
}
return ParentWithID;
}
}
You would load your data into the classes from the database. I had to hard code the values for the example to work:
TreeNode treeNode5 = new TreeNode() { id = "ABCD-12345", parentID = null, name = "Top" };
TreeNode treeNode6 = new TreeNode() { id = "ABCD-12346", parentID = "ABCD-12345", name = "Middle" };
treeNode5.children.Add(treeNode6);
TreeNode treeNode7 = new TreeNode() { id = "ABCD-12347", parentID = "ABCD-12346", name = "Bottom" };
TreeNode treeNode8 = new TreeNode() { id = "ABCD-12348", parentID = "ABCD-12346", name = "Bottom" };
treeNode6.children.Add(treeNode7);
treeNode6.children.Add(treeNode8);
TreeNode topOne = treeNode5.FindParentWithID("ABCD-12346");
topOne will be end up being treeNode6 name="Middle" in this example.

try this code, i have same issue and it works perfectly
this method used to build tree from list of items, by looping through all items, and add each item to its parent's child list. and return only the root item with its nested child.
public TreeNode BuildTree(List<TreeNode> source)
{
// build the children list for each item
foreach (var item in source)
{
var itm = source.Where(i => i.parentID == item.Id).ToList();
item.ChildItems = itm;
}
// return only the root parents with its child inside
return source.Where(i => i.parentID == null).FirstOrDefault();
}
noting that this method return only on TreeNode Object with its child, you can return List by changing .FirstOrDefault() to .ToList() in return line

How to sum the value of child items from a hierarchical list in a loop

How to sum the value of child items from a hierarchical list in a loop.
I need that during the loop in the list the values of the amount and price property contain the sum of these properties of the children.
Below are the two classes to be used to help me solve my problem.
namespace SGP.Dto.Custo
{
public class PlanilhaCusto
{
public int id{ get; set; }
public int parenteId{ get; set; }
public string name { get; set; }
public decimal amount{ get; set; }
public decimal price{ get; set; }
public PlanilhaCusto(int pId, int pParenteId, pName, decimal pAmount, decimal pPrice)
{
id = pId;
parentId = pParentId;
name = pName;
amount = pAmount;
price = pPrice;
}
}
}
namespace SGP.Dto.Custo
{
public class ShowList
{
List<Dto.Custo.PlanilhaCusto> myList = new List<PlanilhaCusto>();
public void Show()
{
myList.Add(new PlanilhaCusto(1, null, "Projetos", 0, 0));
myList.Add(new PlanilhaCusto(2, 1, "Arquitetura", 5,10));
myList.Add(new PlanilhaCusto(3, 1, "Estrutura", 0, 0));
myList.Add(new PlanilhaCusto(4, 3, "Civil", 1, 50));
myList.Add(new PlanilhaCusto(5, 3, "Infra", 3, 75));
myList.Add(new PlanilhaCusto(6, null, "Pessoal", 0, 0));
myList.Add(new PlanilhaCusto(7, 6, "Mão de Obra", 20, 5700));
/*In this loop the value of the parent items must be updated
(calculated). The hierarchy of the list can be unlimited,
like a tree. I tried using a recursive method but I could
not do it.*/
foreach (var itemList in myList)
{
}
}
}
}

Assuming the Elements in the list are sorted the way they are in your example, the fastest way to do this should be to iterate through the list in reverse order and add the amount to the list entry with the correct id.
Iterate backwards through the list
When the current element has a parent add amount and amount*price to it
EDIT:
After reading your comment in your source, i assume you already knew what i just wrote.
My approach would be the following:
for (int i = myList.Count - 1; i > 1; i--)
{
var temp = myList.ElementAt(i);
if (temp.parentId != null)
{
var parent = myList.ElementAt(temp.parentId - 1);
parent.amount += temp.amount;
parent.price += (temp.amount * temp.price);
}
}

for creating a hierarchical structure, i modified your PlanilhaCusto to resemble a sort of a Node in tree, having both parent and children members, for ease the traverse
public class PlanilhaCusto
{
public int Id { get; set; }
public string Name { get; set; }
public int? ParentId { get; set; }
public decimal Amount { get; set; }
public decimal Price { get; set; }
public IEnumerable<PlanilhaCusto> Children { get; set; }
}
Given this structure and an initial input
you can build the entire tree structure regardless of how many levels there are relying on some recursion
public IEnumerable<PlanilhaCusto> Descendants(PlanilhaCusto parent, IEnumerable<PlanilhaCusto> source)
{
var query = from node in source
where node.ParentId == parent.Id
let children = Descendants(node, source)
select new PlanilhaCusto
{
Id = node.Id,
ParentId = node.ParentId,
Name = node.Name,
Amount = node.Amount,
Price = node.Price,
Children = children,
};
return query.ToList();
}
var hierarchy = from node in source
let children = Descendants(node, source)
where node.ParentId == null
select new PlanilhaCusto
{
Id = node.Id,
ParentId = node.ParentId,
Name = node.Name,
Price = node.Price,
Children = children,
};
that would project the initial data source into something similar
and from here you just need to traverse the hierarchy and compose the total price
public decimal? Total(PlanilhaCusto node)
{
decimal? price = node.Price * node.Amount;
if (node.Children != null)
{
foreach (var child in node.Children)
{
price += Total(child);
}
}
return price;
}
var totals = from node in hierarchy
select new
{
Id = node.Id,
Name = node.Name,
Total = Total(node),
};

Displaying self-referencing table's data in a c# application

I have following table:
---------------------
Id Title Parent
---------------------
1 Parent NULL
2 Level_1 1
3 Level_2 1
4 Level_3 1
5 Level NULL
6 Level_New 5
Now I want to display these data in my console application, I know I need a recursive function but no idea how to do it becuase I want to read these data using ADO.NET not EntityFramework.In EF I could define a model that has a navigation property for children:
public class Menu
{
public int Id { get; set; }
public string Title { get; set; }
public int? Parent { get; set; }
public ICollection<Menu> Children { get; set; }
}
But the problem is that I don't want to use EF. I want to do it using raw ADO.NET

Recursion isn't fun, this is a solution that I used to test for a much larger recursion
public class MyObject
{
public string Id;
public string ParentId;
public string Name;
public string Comments;
}
a lot of this code you wont need, but this should give you want you need on recursion.
private void BindTree(IEnumerable<MyObject> list, TreeNode parentNode, string previousNode)
{
var myObjects = list as IList<MyObject> ?? list.ToList();
var nodes = myObjects.Where(x => (parentNode == null ? x.ParentId == "[].[].[(root)]" : x.ParentId == parentNode.Value));
var listOfNodeNames = new List<string>();
foreach (var node in nodes)
{
var newNode = new TreeNode(node.Name, node.Id);
BindTree(myObjects, newNode, previousNode);
}
}
The above code does the recursion I need ( code you wont need stripped out ) and builds a treeview on a page based on data from a datatable.
But, this should give you want you need to do your recursion.

You need to pull data from server first, then construct tree on client side. Beware of circular reference.
First, change your Menu class to ensure that Children will never null
public class Menu
{
public Menu()
{
Children = new HashSet<Menu>();
}
public int Id { get; set; }
public string Title { get; set; }
public int? Parent { get; set; }
public ICollection<Menu> Children { get; private set; }
}
Then pull the data from database, and construct the tree
var connBuilder = new SqlConnectionStringBuilder();
connBuilder.DataSource = "localhost";
connBuilder.InitialCatalog = "YourDatabaseName";
connBuilder.IntegratedSecurity = true;
using (var con = new SqlConnection(connBuilder.ToString()))
{
con.Open();
var list = new List<Menu>();
//pull data from database
using (var cmd = con.CreateCommand())
{
cmd.CommandText = "SELECT Id, Title, Parent FROM [dbo].[YourTableName]";
using (var reader = cmd.ExecuteReader())
{
while (reader.Read())
{
list.Add(new Menu
{
Id = reader.GetInt32(0),
Title = reader.GetString(1),
Parent = reader.IsDBNull(2) ?(int?) null : reader.GetInt32(2)
});
}
}
}
//construct tree
var newList = new List<Menu>();
foreach (var l1 in list)
{
if (l1.Parent == null)
{
newList.Add(l1);
}
foreach (var l2 in list)
{
if (l2.Parent == l1.Id)
{
l1.Children.Add(l2);
}
}
}
// do whatever you want with newList
}
You will get data like this

Convert list of items to list of tree nodes that have children

I have the following class
public class Item
{
public int Id { get; set; }
public int? ParentId { get; set; }
public string Text { get; set; }
}
And the following class for tree view
public class TreeViewModel
{
public TreeViewModel()
{
this.Children = new List<TreeViewModel>();
}
public int Id { get; set; }
public int NodeId { get; set; }
public string Text { get; set; }
public bool Expanded { get; set; }
public bool Checked { get; set; }
public bool HasChildren
{
get { return Children.Any(); }
}
public IList<TreeViewModel> Children { get; private set; }
}
I will receive list of items and I would to convert it to tree.
the item that not have parent id it will the main node.
example: if i have the following items
item[0] = Id:0 Text:User ParentId:3
item[1] = Id:1 Text:Role ParentId:3
item[2] = Id:2 Text:SubUser ParentId:0
item[3] = Id:3 Text:Admin ParentId:null
item[4] = Id:4 Text:SuperAdmin ParentId:null
item[5] = Id:5 Text:Doha ParentId:4
the following item it will list of tree
I tried to make recursive function to do that , but i have no result

You don't need a recursive function to do this:
var models = items.Select(i => new TreeViewModel
{
Id = i.Id,
...
}).ToList();
foreach (var model in models){
model.Children.AddRange(models.Where(m => m.ParentId == model.Id));
}
If you then want to get the roots of your tree, you can use:
var roots = models.Where(m => !m.ParentId.HasValue);

Here is a fast O(N) time complexity method of doing that:
List<Item> list = ...;
// Pre create all nodes and build map by Id for fast lookup
var nodeById = list
.Select(item => new TreeViewModel { Id = item.Id, Text = item.Text })
.ToDictionary(item => item.Id);
// Build hierarchy
var tree = new List<TreeViewModel>();
foreach (var item in list)
{
var nodeList = item.ParentId == null ? tree, nodeById[item.ParentId.Value].Children;
nodeList.Add(nodeById[item.Id]);
}