Baumstruktur aus Liste erzeugen

[Phoenix]

Also erstmal die Baumstruktur:

Code:

// create test data
   var list = new [] {
      new Node() { Id=1, Description="Beschreibung 1", ParentId = 0 },
      new Node() { Id=2, Description="Beschreibung 2", ParentId = 0 },
      new Node() { Id=3, Description="Beschreibung 3", ParentId = 2 },
      new Node() { Id=4, Description="Beschreibung 4", ParentId = 2 },
      new Node() { Id=5, Description="Beschreibung 5", ParentId = 4 },
      new Node() { Id=6, Description="Beschreibung 6", ParentId = 0 },
      new Node() { Id=7, Description="Beschreibung 7", ParentId = 6 },   
   };
   
   // make a lookup to quickly build the structure -> O(n)
   var lookup = list.ToLookup(node => node.ParentId);
   
   // hook up the nodes (also O(n))
   var tree = new List<Node>();   
   foreach (var node in list)
   {
      // if root node, add to tree
      if (node.ParentId == 0)
         tree.Add(node);

      // hook in all children
      node.Children = lookup[node.Id].ToList();
   }

Was das serialisieren nach Json angeht, schau Dir am besten mal Newtonsoft.Json an: https://www.nuget.org/packages/Newtonsoft.Json/
Das ist *das* Library in .NET wenn es um Json geht. Selbst Microsoft setzt in vielen Teilen seiner Web-Libraries inzwischen darauf.

Das ist dann ein Einzeiler:

Code:

string jsonString = JsonConvert.SerializeObject(tree);

Der JsonString sieht dann so aus:

Code:

[
   {"Id":1,"ParentId":0,"Description":"Beschreibung 1","Children":[]},
   {"Id":2,"ParentId":0,"Description":"Beschreibung 2","Children":
      [
         {"Id":3,"ParentId":2,"Description":"Beschreibung 3","Children":[]},
         {"Id":4,"ParentId":2,"Description":"Beschreibung 4","Children":
            [
               {"Id":5,"ParentId":4,"Description":"Beschreibung 5","Children":[]}
            ]
         }
      ]
   },
   {"Id":6,"ParentId":0,"Description":"Beschreibung 6","Children":
      [
         {"Id":7,"ParentId":6,"Description":"Beschreibung 7","Children":[]}
      ]
   }
]