🌿 ng2-tree

🎬 Usage
👀 Demo
🔧 API
🔫 Controller
SystemJS
Changes that should be taken into account in order to migrate from ng2-tree V1 to ng2-tree V2
💡 Want to help?

🎬 Usage

Ok, let's start with an installation - all you need to do is:

npm install --save ng2-tree

Now when you have ng2-tree installed, you are in a few steps from having tree in your application:

Add the TreeModule to your application's module imports section:

import { NgModule } from '@angular/core';
import { AppComponent } from './app.component';
import { BrowserModule } from '@angular/platform-browser';
import { TreeModule } from 'ng2-tree';

@NgModule({
  declarations: [MyComponent],
  imports: [BrowserModule, TreeModule],
  bootstrap: [MyComponent]
})
export class MyModule {}

As soon as the previous step is done we need to give ng2-tree a model to render - this can be accomplished by populating its [tree] attribute with an object that conforms to the TreeModel interface (see API):

// 1 - import required classes and interfaces
import { TreeModel } from 'ng2-tree';

@Component({
  selector: 'myComp',
  // 2 - set [tree] attribute to tree object
  template: `<tree [tree]="tree"></tree>`
})
class MyComponent {
  // 3 - make sure that tree object conforms to the TreeModel interface
  public tree: TreeModel = {
    value: 'Programming languages by programming paradigm',
    children: [
      {
        value: 'Object-oriented programming',
        children: [{ value: 'Java' }, { value: 'C++' }, { value: 'C#' }]
      },
      {
        value: 'Prototype-based programming',
        children: [{ value: 'JavaScript' }, { value: 'CoffeeScript' }, { value: 'Lua' }]
      }
    ]
  };
}

Apart from that, in order to have usable tree in the browser, you need to add ng2-tree styles which you can find in your node_modules/ng2-tree/styles.css

In Angular 2/4 cli projects, modify .angular-cli.json as below:

      "styles": [
        "styles.css",
        "../node_modules/ng2-tree/styles.css"
      ],

And finally, I suppose, you'd want to listen to events generated by ng2-tree (for a full list of supported events look at the API). No problem, this is also easy to do - for example let's add a listener for node was selected kind of events:

// 1 - import required classes and interfaces
import { TreeModel, NodeEvent } from 'ng2-tree';

@Component({
  selector: 'myComp',
  // 2 - listent for nodeSelected events and handle them
  template: `<tree [tree]="tree" (nodeSelected)="logEvent($event)"></tree>`
})
class MyComponent {
  public tree: TreeModel = { ... };

  // 3 - print caught event to the console
  public logEvent(e: NodeEvent): void {
    console.log(e);
  }
}

Voila! That's pretty much it - enjoy 😊

👀 Demo

Feel free to examine the demo and its sources to find out how things are wired. Also, there is another demo built with Angular CLI.

🔧 API

Here is the fully stuffed tree tag that you can use in your templates:

    <tree
      [tree]="tree"
      [settings]="settings"
      (nodeRemoved)="handleRemoved($event)"
      (nodeRenamed)="handleRenamed($event)"
      (nodeSelected)="handleSelected($event)"
      (nodeMoved)="handleMoved($event)"
      (nodeCreated)="handleCreated($event)"
      (nodeExpanded)="handleExpanded($event)"
      (nodeCollapsed)="handleCollapsed($event)"
      (loadNextLevel)="handleNextLevel($event)">
    </tree>

Let's go through every element of this structure one by one.

tree

tree is the selector for TreeComponent which is bundled into TreeModule:

[tree]

tree has a [tree] attribute which needs to be populated with an object implementing TreeModel interface. You can import this interface like below:

import { TreeModel } from 'ng2-tree';

Here is the definition of the TreeModel interface:

interface TreeModel {
  value: string | RenamableNode;
  id: string | number;
  children?: Array<TreeModel>;
  loadChildren?: ChildrenLoadingFunction;
  settings?: TreeModelSettings;
}

As you can see - an object that conforms to this interface has a recursive nature, an example can be seen below:

{
    value: 'Programming languages by programming paradigm',
    children: [
      {
        value: 'Object-oriented programming',
        children: [
          {value: 'Java'},
          {value: 'C++'},
          {value: 'C#'}
        ]
      },
      {
        value: 'Prototype-based programming',
        children: [
          {value: 'JavaScript'},
          {value: 'CoffeeScript'},
          {value: 'Lua'}
        ]
      }
    ]
  }

Property value can be of type string or RenamableNode. RenamableNode gives you an additional control over the way node is renamed and rendered (by rendered I mean its text representation). Here is the definition of the RenamableNode interface:

interface RenamableNode {
  // This method will be invoked in order to apply new value to this kind of node
  setName(name: string): void;

  // This method will be invoked in order to get a text for rendering as a node value
  toString(): string;
}

Here is an example of such a node in the TreeModel object:

{
    value: 'Programming languages by programming paradigm',
    children: [
      {
        value: 'Object-oriented programming',
        children: [
          {
            // I am a RenamableNode. Yeah, that's me :)
            value: <RenamableNode>{
              name: 'Java',
              setName(name: string): void {
                this.name = name;
              },
              toString(): string {
                return this.name;
              }
            }
          },
          {value: 'C++'},
          {value: 'C#'}
        ]
      },
      {
        value: 'Prototype-based programming',
        loadChildren: (callback) => {
          setTimeout(() => {
            callback([
              {value: 'JavaScript'},
              {value: 'CoffeeScript'},
              {value: 'TypeScript'}
            ]);
          }, 5000);
        }
      }
    ]
  };

Load children asynchronously

Another worth noting thing is loadChildren. This function on TreeModel allows you to load its children asynchronously.

{
  value: 'Prototype-based programming',
  loadChildren: (callback) => {
    setTimeout(() => {
      callback([
        {value: 'JavaScript'},
        {value: 'CoffeeScript'},
        {value: 'TypeScript'}
      ]);
    }, 5000);
  }
}

Node that defines this function is collapsed by default. At the moment of clicking 'Expand' arrow, it starts loading its children by calling given function. If loadChildren function is given to the node - children property is ignored. For more details - have a look at the Demo.

Load children using ngrx (or any redux-like library)

You can also load children by changing the tree state using ngrx. The tree can emit an appropriate event notifying you to dispatch a new action in order to load the branch's children.

To enable this feature you should set the TreeModel.emitLoadNextLevel property to true:

const model: TreeModel = {
emitLoadNextLevel : true
}

Now on the first time the node is expanded a LoadNextLevelEvent will be fired (via the loadNextLevel EventEmitter in the tree) containing the node that requested a next level (its children) loading.

In your code make sure you change the tree state and add the children to the model.

In addition the regular NodeExpanded event will be fired.

NOTICE: if both emitLoadNextLevel and loadChildren are provided, the tree will ignore the emitLoadNextLevel and the LoadNextLevelEvent won't be fired.

Configure node via TreeModelSettings

Apart from that TreeModel interface has an optional field called settings of type TreeModelSettings.

Here is an example of its usage:

{
  value: 'Prototype-based programming',
  settings: {
    'static': true,
    'rightMenu': true,
    'leftMenu': true,
    'cssClasses': {
      'expanded': 'fa fa-caret-down fa-lg',
      'collapsed': 'fa fa-caret-right fa-lg',
      'leaf': 'fa fa-lg',
      'empty': 'fa fa-caret-right disabled'
    },
    'templates': {
      'node': '<i class="fa fa-folder-o fa-lg"></i>',
      'leaf': '<i class="fa fa-file-o fa-lg"></i>',
      'leftMenu': '<i class="fa fa-navicon fa-lg"></i>'
    },
    'menuItems': [
        { action: NodeMenuItemAction.Custom, name: 'Foo', cssClass: 'fa fa-arrow-right' },
        { action: NodeMenuItemAction.Custom, name: 'Bar', cssClass: 'fa fa-arrow-right' },
        { action: NodeMenuItemAction.Custom, name: 'Baz', cssClass: 'fa fa-arrow-right'}
      ]
    }
  },
  children: [
    {value: 'JavaScript'},
    {value: 'CoffeeScript'},
    {value: 'Lua'}
  ]
}

static - Boolean - This option makes it impossible to drag a tree or modify it in a some way, though you still can select nodes in the static tree and appropriate events will be generated.
isCollapsedOnInit - Boolean - This option makes a tree to be collapsed on first load (this option cascades to its children).
rightMenu - Boolean - This option allows you to activate (true, by default) or deactivate (false) right menu when clicking with right button of a mouse.
leftMenu - Boolean - This option allows you to activate (true) or deactivate (false, by default) left menu.
cssClasses - Object:
- expanded - String - It specifies a css class (or classes) for an item which represents expanded state of a node. The item is clickable and it transitions the node to the collapsed state
- collapsed - String - It specifies a css class (or classes) for an item which represents collapsed state of a node. The item is clickable and it transitions the node to the expanded state
- leaf - String - It specifies a css class (or classes) for an item which represents a node without an option to expand or collapse - in other words: a leaf node.
- empty - String - Node is considered empty when it has no children. Once this condition is satisfied - appropriate css class will be applied to the node.
templates - Object:
- node - String - It specifies a html template which will be included to the left of the node's value.
- leaf - String - It specifies a html template which will be included to the left of the leaf's value.
- leftMenu - String - It specifies a html template to the right of the node's value. This template becomes clickable and shows a menu on node's click.
menuItems - here you can specify your custom menu items. You should feed an array of NodeMenuItem instances to this setting. Once done - setup a subscription to MenuItemSelectedEvents by listening to (menuItemSelected)="onMenuItemSelected($event)" on the tree.

All options that are defined on a parent are automatically applied to children. If you want you can override them by settings of the child node.

[settings]

Object that should be passed to [settings] must be of type Ng2TreeSettings. This attribute is optional. Right now only one setting is available in there - rootIsVisible. This setting allows you to make a root node of the tree invisible:

const treeSettings: Ng2TreeSettings = {
  rootIsVisible: false
};

By default rootIsVisible equals to true

`Tree` class

Also in the next section, you'll be reading about events generated by the ng2-tree. And here Tree class comes in handy for us, because its instances propagated with event objects. Under the hood, ng2-tree wraps a TreeModel provided by the user in Tree. And Tree in turn has lots of useful methods and properties (like parent, hasChild(), isRoot() etc.)

events (nodeMoved, nodeSelected, nodeRenamed, nodeRemoved, nodeCreated, nodeExpanded, nodeCollapsed)

NodeEvent is the root of the tree events' hierarchy. It defines property node that contains a receiver of the event action (node is an instance of the Tree class).

NodeDestructiveEvent is the parent for all events that cause changes to the structure of the tree or to the node's value.

NodeSelectedEvent

You can subscribe to the NodeSelectedEvent by attaching listener to the (nodeSelected) attribute

    <tree
      [tree]="tree"
      (nodeSelected)="handleSelected($event)">
    </tree>

NodeSelectedEvent has just one property node which contains a Tree object representing selected node.

{node: <Tree>{...}}

NodeMovedEvent

You can subscribe to NodeMovedEvent by attaching listener to (nodeMoved) attribute

    <tree
      [tree]="tree"
      (nodeMoved)="handleMoved($event)">
    </tree>

NodeMovedEvent has two properties node and previousParent both of which contain Tree objects:

node contains a moved node;
previousParent contains a previous parent of the moved node;

{node: <Tree>{...}, previousParent: <Tree>{...}}

NodeRemovedEvent

You can subscribe to NodeRemovedEvent by attaching listener to (nodeRemoved) attribute

    <tree
      [tree]="tree"
      (nodeRemoved)="handleRemoved($event)">
    </tree>

NodeRemovedEvent has a node property, which contains removed node (of type Tree).

{node: <Tree>{...}}

NodeCreatedEvent

You can subscribe to NodeCreatedEvent by attaching listener to (nodeCreated) attribute

    <tree
      [tree]="tree"
      (nodeCreated)="handleCreated($event)">
    </tree>

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.

{node: <Tree>{...}}

NodeRenamedEvent

You can subscribe to NodeRenamedEvent by attaching listener to (nodeRenamed) attribute

    <tree
      [tree]="tree"
      (nodeRenamed)="handleRenamed($event)">
    </tree>

NodeRenamedEvent has three properties:

node contains a node that was renamed ( an instance of Tree).
oldValue contains a value, that node used to have (it might be string or RenamableNode)
newValue contains a new value of the node (it might be string or RenamableNode)

{
  node: <Tree>{...},
  oldValue: <string|RenamableNode>{...},
  newValue: <string|RenamableNode>{...}
}

NodeExpandedEvent

You can subscribe to NodeExpandedEvent by attaching listener to (nodeExpanded) attribute, this event wont fire on initial expansion

    <tree
      [tree]="tree"
      (nodeExpanded)="handleExpanded($event)">
    </tree>

NodeExpandedEvent has a node property of type Tree, which contains an expanded node.

{node: <Tree>{...}}

NodeCollapsedEvent

You can subscribe to NodeCollapsedEvent by attaching listener to (nodeCollapsed) attribute

    <tree
      [tree]="tree"
      (nodeCollapsed)="handleCollapsed($event)">
    </tree>

NodeCollapsedEvent has a node property of type Tree, which contains a collapsed node.

{node: <Tree>{...}}

LoadNextLevelEvent

You can subscribe to LoadNextLevelEvent by attaching a listener to (loadNextLevel) attribute. Relevant for loading children via ngrx (or any redux-inspired library).

    <tree
      [tree]="tree"
      (loadNextLevel)="handleNextLevel($event)">
    </tree>

LoadNextLevelEvent has a node property of the type Tree, which contains a node for which next level (its children) should be loaded.

{node: <Tree>{...}}

🔫 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.

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:

public tree: TreeModel = {
    value: 'Programming languages by programming paradigm',
    id: 1,
    children: [
      {
        value: 'Object-oriented programming',
        id: 2,
        children: [
          {value: 'Java', id: 3},
          {value: 'C++', id: 4},
          {value: 'C#', id 5},
        ]
      },
      {
        value: 'Prototype-based programming',
        id: 6,
        children: [
          {value: 'JavaScript', id: 7},
          {value: 'CoffeeScript', id: 8},
          {value: 'Lua', id: 9},
        ]
      }
    ]
  };

Ids must be unique within a one tree, otherwise, some controllers will be overwritten and you won't be able to acquire them. In order to get a node's controller you need to create an Angular local variable out of tree component via hash binding in the template:

@Component({
  template: '<tree [tree]="tree" #treeComponent></tree>'
})
class TheComponent implements AfterViewInit {
  tree: TreeModel = {
    value: 'Programming languages by programming paradigm',
    id: 1,
    children: [
      {
        value: 'Object-oriented programming',
        id: 2,
        children: [
          {value: 'Java', id: 3},
          {value: 'C++', id: 4},
          {value: 'C#', id 5},
        ]
      },
      {
        value: 'Prototype-based programming',
        id: 6,
        children: [
          {value: 'JavaScript', id: 7},
          {value: 'CoffeeScript', id: 8},
          {value: 'Lua', id: 9},
        ]
      }
    ]
  };

  @ViewChild('treeComponent') treeComponent;

  ngAfterViewInit(): void {
    // ... make use of this.treeComponent ...
  }
}

then by executing this.treeComponent.getControllerByNodeId(PUT_HERE_YOUR_NODE_ID) you'll get an instance of a TreeController (another couple steps and the world is yours =) )

Below are more detailed explanations of the TreeController and its usage. Let's go method by method:

const oopNodeController = this.treeComponent.getControllerByNodeId(2);

select - selects a node

oopNodeController.select();

This method selects the node and unselects all the other nodes, also it fires a select event.

isSelected - checks whether a node is selected

oopNodeController.isSelected();

This method returns true if the node is selected and false if it isn't.

collapse - collapses a node

oopNodeController.collapse();

This method collapses a node if the node is collapsible (for example we cannot collapse a leaf). If the node gets collapsed successfully - a collapse event gets fired.

isCollapsed - check whether a node is collapsed

oopNodeController.isCollapsed();

This method returns true if the node is collapsed and false otherwise.

expand - expands a node

oopNodeController.expand();

This method expands the node in case it can be expanded. On successful expanding the expand event is fired.

expandToParent - expands a node and its parents up to the root

oopNodeController.expandToParent();

This method expands the node even if it is a leaf. Expand event is fired for every expanded parent up to the root.

Important: For this to work - keepNodesInDOM: true should be set on the appropriate tree.

isExpanded - checks whether a node is expanded

oopNodeController.isExpanded();

toTreeModel - converts a tree to a TreeModel instance

Actually controller makes and returns a clone of tree's underlying model

oopNodeController.toTreeModel();

This method returns true if the node is expanded and false otherwise.

rename - renames a node (changes its value underneath)

oopNodeController.rename('new value');

This method accepts a string and sets it as a node's new value, this action also fires rename event.

startRenaming - changes the node template so that text input appears and lets a user type a new name

oopNodeController.startRenaming();

After the user entered the new name a rename event will be fired.

remove - removes a node from the tree

oopNodeController.remove();

This method removes the node and its children and fires remove event.

addChild - creates a new child node

let newNode: TreeModel = {
  value: 'Go',
  children: []
};
oopNodeController.addChild(newNode);

This method accepts a TreeModel and adds it as a child of the parent or as a sibling (depends on which controller this was called - branch controller or a leaf controller).

changeNodeId - changes node's id

oopNodeController.changeNodeId(10);

This method can change a node's id. When the user creates a node from node's menu you will access the new node after it's created and this method will provide a way to change the node's id.

reloadChildren - loads async children once more

oopNodeController.reloadChildren();

setChildren - changes children of a node;

let newChildren: Array<TreeModel> = [
  { value: 'new children 1' },
  { value: 'new children 2' },
  { value: 'new children 3' }
];
oopNodeController.setChildren(newChildren);

This method replaces all existing children of the node with new ones.

SystemJS

If you are using SystemJS, then you need

System.config({
    // ...
    map: {
      // ...
      'ng2-tree': 'node_modules/ng2-tree/bundles/ng2-tree.umd.min.js',
      // ...
    },
    // ...
}

Changes that should be taken into account in order to migrate from ng2-tree V1 to ng2-tree V2

Events were reworked:
- In V1 all events that were inherited from NodeDestructiveEvent used to have property parent. It's not the case anymore. If you need a parent you should get it from node in event object like node.parent;
- All events used to have node property of type TreeModel. Now node is of type Tree (as well as node.parent);
- NodeMovedEvent now has property previousParent, which contains tree in which moved node used to be.
CSS styles in ng2-tree V2 are distributed as separate file which you can find in node_modules/ng2-tree/styles.css. That allows you to override ng2-tree styles more easily.

💡 Want to help?

I am very appreciate for your ideas, proposals and found bugs which you can put in github issues. Thanks in advance!

P.S. If you find it hard going through the documentation, please, let me know which parts of it was difficult to grasp and I will improve them.

ng2-treeAngular tree component