Recursive TreeView in ASP.NET

Question

I have an object of type list from which I wish to use to populate a treeview in asp.net c#.

Each object item has:

id | Name | ParentId

Answer 1

This is a sample with Category entity that references itself. First we should prepare our data source:

public class Category
    {
        public int Id { get; set; }
        public string  Name { get; set; }
        public int? ParentId { get; set; }
        public virtual Category Parent { get; set; }
        public virtual ICollection Children { get; set; }
        public byte[] Image { get; set; }
    }

public class Product
    {
        public int Id { get; set; }
        public string Code { get; set; }
        public string Name { get; set; }
        public Category ProductCategory { get; set; }
        public int ProductCategoryId { get; set; }
        public byte[] Image { get; set; }
    }

public List GethierarchicalTree(int? parentId=null)
        {
            var allCats = new BaseRepository().GetAll();

            return allCats.Where(c => c.ParentId == parentId)
                            .Select(c => new Category()
                            {
                                Id = c.Id,
                                Name = c.Name,
                                ParentId = c.ParentId,
                                Children = GetChildren(allCats.ToList(), c.Id)
                            })
                            .ToList();
        }

        public List GetChildren(List cats, int parentId)
        {
            return cats.Where(c => c.ParentId == parentId)
                    .Select(c => new Category
                    {
                        Id = c.Id,
                        Name = c.Name,
                        ParentId = c.ParentId,
                        Children = GetChildren(cats, c.Id)
                    })
                    .ToList();
        }

Then in our code behind we have:

 protected void Page_Load(object sender, EventArgs e)
        {
            var hierarchicalData = new CategoryRepository().GethierarchicalTree();
            tv1.Nodes.Clear();
            var root = new TreeNode("0","Root");
            tv1.Nodes.Add(root);
            BindTreeRecursive(hierarchicalData, root);
        }

        private void BindTreeRecursive(List hierarchicalData, TreeNode node)
        {
            foreach (Category category in hierarchicalData)
            {
                if (category.Children.Any())
                {
                    var n = new TreeNode(category.Name, category.Id.ToString());
                    node.ChildNodes.Add(n);
                    BindTreeRecursive(category.Children.ToList(), n);
                }
                else
                {
                    var n = new TreeNode(category.Name, category.Id.ToString());
                    node.ChildNodes.Add(n);

                    if (new ProductRepository().Get(a => a.ProductCategoryId == category.Id).Any())
                    {
                        var catRelatedProducts = new ProductRepository().Get(a => a.ProductCategoryId == category.Id).ToList();

                        foreach (Product product in catRelatedProducts)
                        {
                            n.ChildNodes.Add(new TreeNode(product.Name,product.Id.ToString()));
                        }
                    }
                }
            }
        }