diff --git a/kfet/static/kfet/js/kfet.api.js b/kfet/static/kfet/js/kfet.api.js
index 81f0cfe4..e0bc2c35 100644
--- a/kfet/static/kfet/js/kfet.api.js
+++ b/kfet/static/kfet/js/kfet.api.js
@@ -572,75 +572,74 @@ class Article extends ModelObject {
     set price(v) { this._price = floatCheck(v); }
 }
 
+class TreeNode {
+    
+    constructor(type, content) {
+        this.type = type;
+        this.content = content;
+        this.parent = null;
+        this.children = []; 
+    }
+}
+
 
 /**
  * Simple {@link Models.ModelObject} list.
  * @memberof Models
  */
-class ModelList {
+class ModelTree {
 
     /** 
      * Nested structure of the list
      * @abstract
      * @type {Models.ModelObject[]}
      */
-    static get models() { return []; }
+    static get models() { return {}; }
 
-    /** 
-     * Verbose names for list models
-     * @abstract
-     * @type {string[]}
-     */
-    static get names() { 
-        return this.models.map(function(v) {
-            return v.verbose_name;
-        });
-    }
 
     /**
      * Creates empty instance and populates it with data if given
      * @param {Object[]} [datalist=[]]
      */
     constructor(datalist) {
-        this.data = {};
+        this._root = new TreeNode({}) ;
         this.from(datalist || []);
     }
 
     /** 
      * Fetches an object from the instance data, or creates it if
      * it does not exist yet.<br>
-     * Parent objects are created recursively if needed.
+     * If direction >= 0, parent objects are created recursively.
+     * If direction <= 0, child objects are created recursively.
      * @param {number} depth depth on the nested structure of the list
      * @param {Object} data
      */
-    get_or_create(depth, data) {
-        var model = this.constructor.models[depth];
-        var name = model.verbose_name ;
-
-        var existing = this.data[name].find(function (v){
-            return v.id === data['id'] ;
-        }) ;
+    get_or_create(data, direction=0) {
+        var model = this.constructor.models[data.type];
 
+        var existing = this.find(data.type, data.content.id);
         if (existing) {
             return existing;
         }
 
-        if (depth == this.constructor.models.length-1) {
-            var created = new model(data) ;
-            this.data[name].push(created);
-            return created ;
-        } else {
-            var par_name = this.constructor.models[depth+1]
-                               .verbose_name;
+        var content = new this.constructor.models[data.type]();
+        var node = new TreeNode(data.type, content);
 
-            var par_data = data[par_name];
-            var created = new model(data);
-            var parnt = this.get_or_create(depth+1, par_data);
-            created[par_name] = parnt;
-            
-            this.data[name].push(created);
-            return created ;
+        if (direction <= 0) {
+            var parent = data.parent ? this.get_or_create(data.parent, -1) : this._root; 
+            node.parent = parent;
+            parent.children.push(node);
         }
+
+        if (direction >= 0) {
+            for (let child_data of data.children) {
+                var child = this.get_or_create(child_data, 1);
+                child.parent = node;
+                node.children.push(child);
+            }
+        }
+
+        return node ;
     }
 
     /** 
@@ -655,7 +654,7 @@ class ModelList {
         }
 
         for (let data of datalist) {
-            this.get_or_create(0, data);
+            this.get_or_create(data, 0);
         }
     }
 
@@ -728,18 +727,19 @@ class ModelList {
      * @param {class} model
      * @param {Object} props Properties to match
      */
-    find(model, props) {
-        if (this.constructor.models.indexOf(model) == -1) {
-            return undefined ;
-        }
+    find(type, id) {
+        (function recurse(node) {
+            if (node.type === type && node.data.id === id)
+                return node ;
 
-        return this.data[model.verbose_name].find(function(v) {
-            for (let key in props) {
-                if (v[key] !== props[key])
-                    return false;
+            for (let child of node.children) {
+                var result = recurse(child) ;
+                if (result)
+                    return result;
             }
-            return true;
-        });
+
+            return null;
+        })(this._root;)
     }
 }