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🌿 ng2-tree

ng2-tree is a simple Angular 2 component for visualizing data that can be naturally represented as a tree.

🎬 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 need to add it to your component's template and to the list of its directives:

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

@Component({
  selector: 'myComp',
  // 2 - add ng2-tree to the template
  template: `
    <tree [tree]="tree"></tree>
    `,
  // 3 - add TreeComponent to the list of directives
  directives: [BranchyComponent]
})
class MyComponent {
  ...
}

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 confirms to TreeModel interface (see API):

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

@Component({
  selector: 'myComp',
  // 2 - set [tree] attribute to tree object
  template: `
    <tree [tree]="tree"></tree>
    `,
  directives: [TreeComponent]
})
class MyComponent {
  // 3 - make sure tree object confirms to TreeModel interface
  private 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 I suppose you'd want to listen to tree events (for a full list of supported events look at API). No problem, this is also easy to do - for example let's add a listener for node was selected events:

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

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

  // 3 - print caught event to the console
  private 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.

🔧 API

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

    <tree
      [tree]="tree"
      (nodeRemoved)="handleRemoved($event)"
      (nodeRenamed)="handleRenamed($event)"
      (nodeSelected)="handleSelected($event)"
      (nodeMoved)="handleMoved($event)"
      (nodeCreated)="handleCreated($event)">
    </tree>

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

tree

tree is the selector for TreeComponent which you can import like shown below:

import {TreeComponent} from 'ng2-tree';

[tree]

tree has [tree] attribute which need to be populated with an object implementing TreeModel interface. You can import this interface as following

import {TreeModel} from 'ng2-tree';

Here is the definition of TreeModel interface:

interface TreeModel {
  value: string | RenamableNode;
  children?: Array<TreeModel>;
}

As you can see it is recursive and can be represented as the following object:

{
    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 additional control over the way node is renamed and rendered (by rendered I mean its text representation). Here is the definition of RenamableNode interface:

interface RenamableNode {
  setName(name: string): void;
  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: [
          {
            value: <RenamableNode>{
              name: 'Java',
              setName(name: string): void {
                this.name = name;
              },
              toString(): string {
                return this.name;
              }
            }
          },
          {value: 'C++'},
          {value: 'C#'},
        ]
      },
      {
        value: 'Prototype-based programming',
        children: [
          {value: 'JavaScript'},
          {value: 'CoffeeScript'},
          {value: 'TypeScript'},
        ]
      }
    ]
  };

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

Here is the diagram that shows tree events' hierarchy

tree events hierarchy

NodeEvent is the root of tree events' hierarchy. It defines property node that contains a receiver of the event's action (node confirms to TreeModel).

NodeDestructiveEvent is the parent for all events that cause changes to a structure of the tree or to a node value. It defines property parent that contains an object implementing TreeModel interface and gives context to the event's action.

NodeSelectedEvent

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

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

NodeSelectedEvent has just one property node which contains TreeModel object of a selected node.

{node: <TreeModel>{...}}

NodeSelectedEvent inherits its property directly from NodeEvent.

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 parent both of which contain TreeModel objects. node contains moved node. parent contains new parent of the moved node.

{node: <TreeModel>{...}, parent: <TreeModel>{...}}

NodeMovedEvent inherits its properties from NodeDestructiveEvent.

NodeRemovedEvent

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

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

NodeRemovedEvent has two properties node and parent both of which contain TreeModel objects. node contains removed node. parent contains parent of the removed node.

{node: <TreeModel>{...}, parent: <TreeModel>{...}}

NodeRemovedEvent inherits its properties from NodeDestructiveEvent.

NodeCreatedEvent

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

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

NodeCreatedEvent has two properties node and parent both of which contain TreeModel objects. node contains created node. parent contains parent of the newly created node.

{node: <TreeModel>{...}, parent: <TreeModel>{...}}

NodeCreatedEvent inherits its properties from NodeDestructiveEvent.

NodeRenamedEvent

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

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

NodeRenamedEvent has four properties:

  • node contains node that was renamed (implements TreeModel).
  • parent contains parent (implements TreeModel) for the renamed node.
  • oldValue contains value node used to have (it might be string or RenamableNode)
  • newValue contains new value of the node (it might be string or RenamableNode)
{
  node: <TreeModel>{...},
  parent: <TreeModel>{...},
  oldValue: <string|RenamableNode>{...},
  newValue: <string|RenamableNode>{...}
}

NodeRenamedEvent inherits its node and parent properties from NodeDestructiveEvent.

👎 Bad parts

Currently I feel really bad because of two things:

  • ng2-tree doesn't have tests (yet), so I wouldn't recommend you to use this in a production environment
  • ng2-tree doesn't have proper mechanism for customizing its look

👍 Good parts

I really want to deminish all the Bad parts and extend ng2-tree with a new stuff

💡 Want to help?

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

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