Query for updating a node in hierarchial tree structure
A typical example is a table in a relational database where each record’s “parent” field references the primary key of another record.
Of course, Tree cannot only use data originating from a database, but anything: you supply the data, and Tree uses it, regardless of where the data came from and how it was processed.
You need to maintain the closure table alongside your categories table.
The best way is probably to use triggers, but it is somewhat complex to correctly track inserts/updates/deletes for closure tables.
The tables of a relational database are not hierarchical (like XML), but are simply a flat list. In the end - got more-or-less simple, relatively fast, and SIMPLE solution.
Here is how I mapped these: Also, I did not use a sproc to update the node mappings. Tree Hierarchy t ' SET @sql = @sql ') ' EXECUTE (@sql) END I knew that there must be something wrong with this solution. Using this solution, EF6 require another package of hacks to manage a simple tree (fe. So finally I've found a simple solution but combined with this approach.
So I'm left with a few options 1) Create query, order by depth and then create a custom class in C#, populating it one depth at a time. Note that so far I haven't included your Lineage or Depth properties. Remember also when you will try to save sub-node, then do it just this way: An analogy would be a file structure on disk.
2) Find some way to eager load the data in EF, I don't think it is possible for an unlimited amount of levels, only a fixed amount. You are right, EF doesn't work well for generating nested hierarchical queries with the above relationships. The current user has access to a subset of files on the system. Category ancestor Category) private static int Add To Ancestors(Model.
What I finally settled on was the addition of a new gerund entity, along with 2 new entity properties: While writing this up, hazzik posted an answer that is very similar to this approach. As the user opens nodes in the file system tree, we only want to show that user nodes that will, eventually, lead them to the files they can see.
I'll continue writing up though, to provide a slightly different alternative. We don't want to show them file paths to files they do not have access to (for security reasons, e.g., leaking the existence of a document of a certain type). Leaf ID from Nodes n inner join descendants d on n. Node ID ) SELECT * from descendants ) SELECT [Extent1].[Node ID] AS [Node ID], [Extent1].[Name] AS [Name], [Extent1].[Parent Node ID] AS [Parent Node ID], [Extent1].[Leaf ID] AS [Leaf ID] FROM [dbo].[Nodes] AS [Extent1] WHERE ([Extent1].[Parent Node ID] = @p__linq__0) AND ( EXISTS (SELECT 1 AS [C1] FROM ( SELECT [Extent2].[Leaf ID] AS [Leaf ID] FROM [dbo].[Descendants Of]([Extent1].[Node ID]) AS [Extent2] ) AS [Project1] WHERE EXISTS (SELECT 1 AS [C1] FROM ( SELECT 1 AS X ) AS [Single Row Table1] WHERE [Project1].[Leaf ID] = 17 ) )) public void Handle(Parent Changed e) private static void Remove From Ancestors(Model.