fix(TreeController): populate new nodes with ids unless they have them.

Closes #145

README.md

@@ -450,7 +450,7 @@ You can subscribe to `NodeCreatedEvent` by attaching listener to `(nodeCreated)`
 `NodeCreatedEvent` has a `node` property of type `Tree`, which contains a created node and a `controller` property, which will give you access to node's controller.
 
 ```typescript
-{node: <Tree>{...}, controller: <TreeController>{...}}
+{node: <Tree>{...}}
 ```
 
 #### NodeRenamedEvent
@@ -531,7 +531,11 @@ Relevant for loading children via ngrx (or any redux-inspired library).
 ```
 
 ## :gun: Controller
-First of all you should know how to get a controller of a particular node. You can get a controller of a node only if you set an id property of a node. For example, your tree structure should look like:
+First of all you should know how to get a controller of a particular node. You can get a controller of a node only if you set an id property of a node.
+
+> TIP: Ids for nodes created via the context menu or using a TreeController instance get populated automatically unless nodes had ids before there were added to the tree
+
+For example, your tree structure should look like:
 
 ```typescript
 public tree: TreeModel = {

package.json

@@ -93,5 +93,8 @@
     "typescript": "2.4.2",
     "webpack": "3.8.1",
     "zone.js": "0.8.18"
+  },
+  "dependencies": {
+    "uuid": "3.1.0"
   }
 }

src/tree.ts

@@ -14,6 +14,8 @@ import {
 import { Observable, Observer } from 'rxjs/Rx';
 import { TreeModel, RenamableNode, FoldingType, TreeStatus, TreeModelSettings, ChildrenLoadingFunction } from './tree.types';
 
+import * as uuidv4 from 'uuid/v4';
+
 enum ChildrenLoadingState {
   NotStarted,
   Loading,
@@ -201,6 +203,8 @@ export class Tree {
       tree.markAsNew();
     }
 
+    tree.id = tree.id || uuidv4();
+
     if (this.childrenShouldBeLoaded() && !(this.childrenAreBeingLoaded() || this.childrenWereLoaded())) {
       return null;
     }

test/tree.spec.ts

@@ -383,6 +383,10 @@ describe('Tree', () => {
 
     expect(servantTree.hasChild(child)).toEqual(true);
     expect(child.value).toEqual('');
+
+    expect(child.id).toBeDefined();
+    expect(child.id).toEqual(jasmine.any(String));
+
     expect(child.children).toEqual(null);
     expect(child.isLeaf()).toEqual(true);
     expect(child.isNew()).toEqual(true);