C# Online Compiler | .NET Fiddle

<no name> by Anonymous

using System;
using System.Collections.Generic;
using System.Linq;

namespace Sample
{
    public static class Extensions
    {
        public static IEnumerable<T> Flatten<T>(this T source, Func<T, IEnumerable<T>> selector)
        {
            return selector(source).SelectMany(c => Flatten(c, selector))
                                   .Concat(new[] { source });
        }
    }
	
	public class ModelType
    {
        public string ModelTitle;
        public long ModelId;
    }

    public class CodeType
    {
        public string CodeValue;
    }
	
	public class NodeType
    {
        public string NodeTypeDescription { get; set; }
        public object Item { get; set; }
        public NodeType[] Node { get; set; }        
    }
	
	public class Program
    {
        public static void Main()
        {

            var NodeTypes = new NodeType[] {
                new NodeType{
                         NodeTypeDescription = "First Level",
                         Item = new CodeType(){  CodeValue = "01" },
                         Node = new NodeType[]{
                            new NodeType{
                                NodeTypeDescription = "First Child Level 0101",
                                Item = new CodeType(){  CodeValue = "0101" },
                                Node = new NodeType[]{
                                    new NodeType{
                                        NodeTypeDescription = "Target Level Description",
                                        Item = new ModelType(){ ModelId = 1234, ModelTitle = "Target-1234" },
                                        Node = null
                                    }
                                }
                            },
                            new NodeType{
                                NodeTypeDescription = "First Child Level 0102",
                                Item = new CodeType(){  CodeValue = "0102" },
                                Node = new NodeType[]{
                                    new NodeType{
                                        NodeTypeDescription = "Target Level Description",
                                        Item = new ModelType(){ ModelId = 2345, ModelTitle = "Target-2345" },
                                        Node = null
                                    }
                                }
                            }
                         }
                },
                new NodeType{
                         NodeTypeDescription = "Second Level",
                         Item = new CodeType(){  CodeValue = "02" },
                         Node = new NodeType[]{
                            new NodeType{
                                NodeTypeDescription = "Second Child Level 0201",
                                Item = new CodeType(){  CodeValue = "0201" },
                                Node = new NodeType[]{
                                    new NodeType{
                                        NodeTypeDescription = "Second Child Level 020101",
                                        Item = new CodeType(){  CodeValue = "020101" },
                                        Node = new NodeType[]{
                                            new NodeType{
                                                NodeTypeDescription = "Target Level Description",
                                                Item = new ModelType(){ ModelId = 2345, ModelTitle = "Target-2345" },
                                                Node = null
                                            }
                                        }
                                    }
                                }
                            },
                            new NodeType{
                                NodeTypeDescription = "Second Child Level 0202",
                                Item = new CodeType(){  CodeValue = "0202" },
                                Node = new NodeType[]{
                                    new NodeType{
                                        NodeTypeDescription = "Target Level Description",
                                        Item = new ModelType(){ ModelId = 3456, ModelTitle = "Target-3456" },
                                        Node = null
                                    }
                                }
                            }
                         }
                }
            };


            var result = NodeTypes[0].Flatten(x => x.Node).Where(y => ((ModelType)(y.Item)).ModelId == 2345);

        }
    }
}

​x
 
using System;
using System.Collections.Generic;
using System.Linq;
​
namespace Sample
{
    public static class Extensions
    {
        public static IEnumerable<T> Flatten<T>(this T source, Func<T, IEnumerable<T>> selector)
        {
            return selector(source).SelectMany(c => Flatten(c, selector))
                                   .Concat(new[] { source });
        }
    }
    
    public class ModelType
    {
        public string ModelTitle;
        public long ModelId;
    }
​
    public class CodeType
    {
        public string CodeValue;
    }
    
    public class NodeType
    {
        public string NodeTypeDescription { get; set; }
        public object Item { get; set; }
        public NodeType[] Node { get; set; }        
    }
    
    public class Program
    {
        public static void Main()
        {
​
            var NodeTypes = new NodeType[] {
                new NodeType{
                         NodeTypeDescription = "First Level",
                         Item = new CodeType(){  CodeValue = "01" },
                         Node = new NodeType[]{
                            new NodeType{
                                NodeTypeDescription = "First Child Level 0101",
                                Item = new CodeType(){  CodeValue = "0101" },
                                Node = new NodeType[]{
                                    new NodeType{
                                        NodeTypeDescription = "Target Level Description",
                                        Item = new ModelType(){ ModelId = 1234, ModelTitle = "Target-1234" },
                                        Node = null
                                    }
                                }
                            },
                            new NodeType{
                                NodeTypeDescription = "First Child Level 0102",
                                Item = new CodeType(){  CodeValue = "0102" },
                                Node = new NodeType[]{
                                    new NodeType{
                                        NodeTypeDescription = "Target Level Description",
                                        Item = new ModelType(){ ModelId = 2345, ModelTitle = "Target-2345" },
                                        Node = null
                                    }
                                }
                            }
                         }
                },
                new NodeType{
                         NodeTypeDescription = "Second Level",
                         Item = new CodeType(){  CodeValue = "02" },
                         Node = new NodeType[]{
                            new NodeType{
                                NodeTypeDescription = "Second Child Level 0201",
                                Item = new CodeType(){  CodeValue = "0201" },
                                Node = new NodeType[]{
                                    new NodeType{
                                        NodeTypeDescription = "Second Child Level 020101",
                                        Item = new CodeType(){  CodeValue = "020101" },
                                        Node = new NodeType[]{
                                            new NodeType{
                                                NodeTypeDescription = "Target Level Description",
                                                Item = new ModelType(){ ModelId = 2345, ModelTitle = "Target-2345" },
                                                Node = null
                                            }
                                        }
                                    }
                                }
                            },
                            new NodeType{
                                NodeTypeDescription = "Second Child Level 0202",
                                Item = new CodeType(){  CodeValue = "0202" },
                                Node = new NodeType[]{
                                    new NodeType{
                                        NodeTypeDescription = "Target Level Description",
                                        Item = new ModelType(){ ModelId = 3456, ModelTitle = "Target-3456" },
                                        Node = null
                                    }
                                }
                            }
                         }
                }
            };
​
​
            var result = NodeTypes[0].Flatten(x => x.Node).Where(y => ((ModelType)(y.Item)).ModelId == 2345);
​
        }
    }
}
​
​

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