Node-by-Node Tree Building

[VaslD]

Since there is no documentation or example/demo code, I'm having a hard time figuring out a particular use case just by looking at class and method names... 😭 I've seen the tutorial, it isn't exactly helping. I think it's for a different use case.

So what I wanted to do is using this library as a plug-and-play visualizer. I've polymorphic hierarchical data (entities) saved in non-hierarchical formats that will be loaded at runtime; I've written models (classes) covering polymorphism that abstractly each should be considered Nodes; and I've got independent pretty print logic that if given the root of the tree will do whatever it does. Now I'm missing the link on how to construct a ReadOnlyEntityTree(Node) or MutableEntityTree(Node) using this library.

I think the easiest way to fill the gap is constructing such a tree node-by-node starting from newing a node as tree root then adding children to it (and its children) as soon as new data comes in. But all these constructors that take either IEnumerable or IEntityDefinition confuses me. It seems I can only construct a tree when I have all the data and have their relationship mapped out?

I'm also not sure how to store different types in the same tree. Adding a common base class to all data models (or use object) will solve this problem but it's kinda a dirty trick. I don't want to use it if there's better solution available. Is the generic type parameter <TItem> strictly enforced on all nodes that can link to this particular node?

[diyradiolab]

Did you find a solution to your last paragraph? I’ve tried all day. When I add children the root nodes Id is assigned to the children causing an idea related to duplicate IDs.

[VaslD]

I don’t think so. Sorry.

This was a post from about 3 years ago. I guess I ended up using another library but I honestly don’t remember anything about this.

I mean no disrespect to the maintainer. But considering this library was last updated in 2019, you’d find better libraries faster than trying to solve a quarter-decade old problem building with this library.

[PatchouliTC]

Did you find a solution to your last paragraph? I’ve tried all day. When I add children the root nodes Id is assigned to the children causing an idea related to duplicate IDs.

I find it seems very easy to use
e.g. MutableEntityTreeNode
first create a package around which entity you want to use in tree as tree node

    //your code model which will use in that tree
    public class CategoryItem
    {
        public CategoryItem(long contentId, string name)
        {
            CategoryId = contentId;
            Name = name;
        }

        public long CategoryId { get; }
        public string Name { get; set; }
    }

    //create simple tree entity option package
    public class CategoryEntityDefinition<TValue> : EntityDefinition<long, TValue>
    where TValue : CategoryItem
    {
        public static readonly CategoryEntityDefinition<TValue> Instance = new CategoryEntityDefinition<TValue>();

        //tell tree about how to understand your model (like which is sql unique id)
        //and tell tree how to compare each model if tree meet same id tree node
        private CategoryEntityDefinition() : base(c => c.CategoryId,EqualityComparer<CategoryItem>.Default)
        { }
    }
    //create your model-tree node package
    public class SimpleMutableCategoryNode : MutableEntityTreeNode<SimpleMutableCategoryNode, long, CategoryItem>
    {
        //create new node with target item
        //also init EntityDefinition
        //you can set how to check errors[e.g. avoid cycles,doc say all errors]
        public SimpleMutableCategoryNode(CategoryItem item)
            : base(CategoryEntityDefinition<CategoryItem>.Instance, item, ErrorCheckOptions.All)
        { }

        private SimpleMutableCategoryNode(CategoryItem item, SimpleMutableCategoryNode parent)
            : base(item, parent)
        { }

        protected override SimpleMutableCategoryNode Create(CategoryItem value, SimpleMutableCategoryNode parent)
        {
            return new SimpleMutableCategoryNode(value, parent);
        }

        //protected override void SetItemName(string name)
        //{
        //    Item.Name = name;
        //}

        //error check,if you need output console output
        protected override bool ContinueAddOnExistingError()
        {
            Console.WriteLine($"Cancelled adding to {Id} {Item.Name} due to error: {Error}");

            return false;
        }
    }

after this define,each SimpleMutableCategoryNode is a basic root or a node, you can use it as root or node and do what you want
such as,is easy to create the tree like that:

            var root = new SimpleMutableCategoryNode(new CategoryItem(1, "a"));
            root.AddChild(new CategoryItem(2, "b"));
            root.AddChild(new CategoryItem(3, "c"));
            root[2].AddChild(new CategoryItem(3, "c1"));
            Console.WriteLine("\n" + root.ToString((n) => {
                if (n == null) return "<null>";
                var error = n.Error.Normalize();
                var errorStr = error != IdentityError.None ? $"[** {error} **]" : "";
                return $"{n.Id}-{n.Item.Name} [{n.HierarchyId.ToString("/")}] {errorStr}";
            }));

if you want to merge two diff tree,you can use attach method(it allows you attach SimpleMutableCategoryNode to other root/node )

            var root = new SimpleMutableCategoryNode(new CategoryItem(1, "a"));
            var rootb= new SimpleMutableCategoryNode(new CategoryItem(10, "z"));
            root.AddChild(new CategoryItem(2, "b"));
            root.AddChild(new CategoryItem(3, "c"));
            root[2].AddChild(new CategoryItem(4, "d"));
            root[4].AttachChild(rootb);

and if you want to serialize a basic tree data and create a tree,use SerialTreeNode

    public class CategoryDataNode : SerialTreeNode<CategoryDataNode>
    {
        public CategoryDataNode() { }

        public CategoryDataNode(long categoryId, string name, params CategoryDataNode[] children) 
            : base(children)
        {
            CategoryId = categoryId;
            Name = name;
        }
        
        public long CategoryId { get; set; }
        public string Name { get; set; }
    }

this define what your serialize tree data looks like:

        {
          "CategoryId": 140,
          "Name": "Communication & Collaboration",
          "Children": [
            {
              "CategoryId": 334,
              "Name": "Digital Art & Imaging",
              "Children": [
              ]
            }
          ]
        }

and after that you will get a CategoryDataNode which contains all tree struct
then transform this CategoryDataNode to a SimpleMutableCategoryNode<--this will be this tree struct root

//manual transform CategoryDataNode to CategoryItem
var _root = new SimpleMutableCategoryNode(new CategoryItem(dataRoot.CategoryId));
//tell method that you want to create a tree,tree root is _root ,incoming data source is dataRoot,each node in dataRoot will use n => new CategoryItem(n.CategoryId) to transform CategoryDataNode to CategoryItem
_root.Build(dataRoot, n => new CategoryItem(n.CategoryId));

the main question is you must make sure id is unique,i suggest you can use some nuget package like IdGen(snowflake,generate unique long id) to get ids