How to use Immutable JS with typed ES6 classes?

Question

Say I have classes Task and TaskGroup

class Task{
     constructor(public text:string){}
}

class TaskGroup {
    constructor(public title:string = "new task group", public tasks:Task[] = []){}
}

Then in my Angular 2 service I will create an Immutable List of TaskGroups

@Injectable()
class TaskService {
    taskGroups:Immutable.List<TaskGroup>;

    constructor() {
       this.taskGroups = Immutable.List<TaskGroup>([new TaskGroup("Coding tasks")]);
    }
}

This way only taskGroups List is immutable. Whatever is inside it isn't. Even if I do Immutable.fromJS(...) instead of Immutable.List<Board>(...) the nested objects are plain ol' Javascript objects.

Immutable JS doesn't supposed class inheritance (Inheriting from Immutable object with ES6 #562)

//can't do this!
class TaskGroup extends Immutable.Map<string, any>{
    constructor(public title:string = "new task group", public tasks:Task[]){}
}
//it complained about the class not having methods like set, delete etc

So how to create Immutable class objects?

You might want to have a look at this [link](http://blog.scottlogic.com/2016/01/05/angular2-with-immutablejs.html) ;) — Kutyel, Jan 12 '16 at 19:20
@Kutyel the wrapper is a nice concept. Perhaps you should write it as an answer and link to the article. — Frozen Crayon, Jan 13 '16 at 06:30

score 9 · Answer 1 · edited Oct 08 '17 at 17:47

9

You can do like this:

const TodoRecord = Immutable.Record({
    id: 0,
    description: "",
    completed: false
});

class Todo extends TodoRecord {
    id:number;
    description:string;
    completed: boolean;

    constructor(props) {
        super(props);
    }
}

let todo:Todo = new Todo({id: 1, description: "I'm Type Safe!"});

Not perfect but working.

It comes from this great blog post: https://blog.angular-university.io/angular-2-application-architecture-building-flux-like-apps-using-redux-and-immutable-js-js/

edited Oct 08 '17 at 17:47

Matthew Simoneau

6,199
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answered Jan 12 '16 at 16:05

bertrandg

3,147
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2

It is not type checking the constructor arguments. Pass string for id and it works! – Frozen Crayon Jan 13 '16 at 13:18

score 4 · Answer 2 · answered Jan 13 '16 at 06:54

You can make a wrapper with Immutable, as stated in this tutorial:

import { List, Map } from 'immutable';

export class TodoItem {
  _data: Map<string, any>;

  get text() {
    return <string> this._data.get('text');
  }

  setText(value: string) {
    return new TodoItem(this._data.set('text', value));
  }

  get completed() {
    return <boolean> this._data.get('completed');
  }

  setCompleted(value: boolean) {
    return new TodoItem(this._data.set('completed', value));
  }

  constructor(data: any = undefined) {
    data = data || { text: '', completed: false, uuid: uuid.v4() };
    this._data = Map<string, any>(data);
  }
}

Hope this will help! ;)

How to use Immutable JS with typed ES6 classes?

2 Answers2

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