Hierarchical Data From Parent Child-CodePudding

 public class Hierarchy
    {
        public int Id { set; get; }
        public int? ParentId { set; get; }
        public int Level { set; get; }
    }

    class Program
    {

        public static List<Hierarchy> GetData()
        {
            List<Hierarchy> hierarchies = new List<Hierarchy>()
        {
             new Hierarchy(){ Id = 1 , ParentId= null, Level = 0   },
             new Hierarchy(){ Id = 2 , ParentId= 1 , Level = 1},
             new Hierarchy(){ Id = 3 , ParentId= 1, Level = 1 },
             new Hierarchy(){ Id = 4 , ParentId= 2, Level = 2 },
             new Hierarchy(){ Id = 5 , ParentId= 2, Level = 2 },
             new Hierarchy(){ Id = 6 , ParentId= 3, Level = 2 },
             new Hierarchy(){ Id = 7 , ParentId= 3, Level = 2 },
             new Hierarchy(){ Id = 8 , ParentId= 4, Level = 3 },
        };

            return hierarchies;

        }

        public static List<Hierarchy> GetTree(List<int> Ids, List<Hierarchy> hierarchies)
        {

            foreach (var item in Ids)
            {

                var result = GetData().Where(x => x.ParentId == item).Select(x => x.Id).ToList();

                Hierarchy hierarchy = new Hierarchy();
                hierarchy.Id = item;
                hierarchy.ParentId = GetData().FirstOrDefault(x => x.Id == hierarchy.Id).ParentId;
                hierarchy.Level = GetData().FirstOrDefault(x => x.Id == hierarchy.Id).Level;
                hierarchies.Add(hierarchy);


                GetTree(result, hierarchies);
            }


            return hierarchies;


        }

        static void Main(string[] args)
        {
            List<int> Ids = new List<int>();
            Ids.Add(1);
            List<Hierarchy> hierarchies = new List<Hierarchy>();

            GetTree(Ids, hierarchies);

            foreach (var item in hierarchies)
            {
                Console.WriteLine(item.Id);
            }
        }
    }

I need to get Hierarchical data for report printing I need to traverse through each node from top to bottom and again from top to bottom

tried and getting 1 -> 2 -> 4 -> 8 -> 5 - > 3 -> 6 -> 7

expected output 1 -> 2 -> 4 - > 5 -> 8 then again from top 1 -> 3 - > 6 - > 7 in a single collection

I tried to write recursive function and it give me data through all node but it does not match with my requirement

CodePudding user response：

The output cannot be a List<Hierarchy> is you want each path from top to bottom. What you need is a List<List<Hierarchy>>.

Here's are the pair of functions that do it.

public static List<List<Hierarchy>> GetTree(ILookup<int?, Hierarchy> lookup) =>
    GetTree(lookup, null);

private static List<List<Hierarchy>> GetTree(ILookup<int?, Hierarchy> lookup, int? parent)
{
    var output = new List<List<Hierarchy>>();
    var children = lookup[parent];
    foreach (var child in children)
    {
        var grandchildren = GetTree(lookup, child.Id);
        if (grandchildren.Any())
        {
            foreach (var grandchild in grandchildren)
            {
                output.Add(grandchild.StartWith(child).ToList());
            }
        }
        else
        {
            output.Add(new List<Hierarchy>() { child });
        }
    }
    return output;
}

The ILookup<int?, Hierarchy> lookup is a LINQ interface that allows to to produce an IEnumberable<Hierarchy> for any ParentId passed in.

GetTree(ILookup<int?, Hierarchy> lookup, int? parent) recursively runs down the tree when it finds a child has grandchildren and when a child doesn't it returns just that child. It then builds each list as it recurses back up the call stack.

When I run this code:

List<Hierarchy> data = GetData();
ILookup<int?, Hierarchy> lookup = data.ToLookup(x => x.ParentId);
List<List<Hierarchy>> result = GetTree(lookup);
foreach (List<Hierarchy> rs in result)
{
    Console.WriteLine(String.Join(" -> ", rs.Select(r => r.Id)));
}

I get out this:

1 -> 2 -> 4 -> 8
1 -> 2 -> 5
1 -> 3 -> 6
1 -> 3 -> 7

CodePudding user response：

 public class Hierarchy
    {
        public Hierarchy()
        {
            Children = new List<Hierarchy>();
        }
        public int Id { set; get; }
        public int? ParentId { set; get; }
        public int Level { set; get; }

        public List<Hierarchy> Children { set; get; }

    }
    class Program
    {
        public static List<Hierarchy> GetData()
        {
            List<Hierarchy> hierarchies = new List<Hierarchy>()
        {
             new Hierarchy(){ Id = 1 , ParentId= null, Level = 0 },
             new Hierarchy(){ Id = 2 , ParentId= 1 , Level = 1},
             new Hierarchy(){ Id = 3 , ParentId= 1, Level = 1 },
             new Hierarchy(){ Id = 4 , ParentId= 2, Level = 2 },
             new Hierarchy(){ Id = 5 , ParentId= 2, Level = 2 },
             new Hierarchy(){ Id = 6 , ParentId= 3, Level = 2 },
             new Hierarchy(){ Id = 7 , ParentId= 3, Level = 2 },
             new Hierarchy(){ Id = 8 , ParentId= 4, Level = 3 },
             new Hierarchy(){ Id = 9 , ParentId= 5, Level = 3 },
             new Hierarchy(){ Id = 10 , ParentId= 7, Level = 3 },
        };

            return hierarchies;

        }
        public static IEnumerable<Hierarchy> GetNodes(Hierarchy node)
        {
            if (node == null)
            {
                yield
                break;
            }

            yield
            return node;
            foreach (var n in node.Children)
            {
                foreach (var innerN in GetNodes(n))
                {
                    yield
                    return innerN;
                }
            }
        }
        public static List<Hierarchy> GethierarchicalTree(int? parentId = null)
        {
            var all = GetData();

            return all.Where(c => c.ParentId == parentId)
                            .Select(c => new Hierarchy()
                            {
                                Id = c.Id,
                                Level = c.Level,
                                ParentId = c.ParentId,
                                Children = GetChildren(all, c.Id)
                            })
                            .ToList();
        }
        public static List<Hierarchy> GetChildren(List<Hierarchy> hierarchies, int parentId)
        {
            return hierarchies.Where(c => c.ParentId == parentId)
                    .Select(c => new Hierarchy
                    {
                        Id = c.Id,
                        ParentId = c.ParentId,
                        Level = c.Level,
                        Children = GetChildren(hierarchies, c.Id)
                    })
                    .ToList();
        }

        static void Main(string[] args)
        {
            var re = GethierarchicalTree(1);

            var parent = GetData().FirstOrDefault(x => x.ParentId == null);

            List<Hierarchy> lst = new List<Hierarchy>();

            foreach (var item in re)
            {
                var rxt = GetNodes(item).OrderBy(x => x.Level).ToList();
                lst.Add(parent);
                lst.AddRange(rxt);

            }

            foreach (var item in lst)
            {
                Console.WriteLine("Id :"   item.Id   " Parent :"   item.ParentId);
            }

        }
    }

thanks for your help I have figured it out by myself