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Author message:

Please use new @angular-extensions/model package which brings same functionality and much better tooling with build in schematics, support for ng add and tree-shakeable providers. Migration should be extremely simple, please check the documentation of the new package.

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6.0.2 • Public • Published

The Angular Model - ngx-model

by @tomastrajan

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Simple state management with minimalistic API, one way data flow, multiple model support and immutable data exposed as RxJS Observable.


ngx-model dataflow diagram

Getting started

  1. Install ngx-model

    npm install --save ngx-model


    yarn add ngx-model
  2. Import and use NgxModelModule in you AppModule (or CoreModule)

    import { NgxModelModule } from 'ngx-model';
      imports: [
    export class CoreModule {}
  3. Import and use Model and ModelFactory in your own services.

    import { Injectable } from '@angular/core';
    import { Observable } from 'rxjs';
    import { ModelFactory, Model } from 'ngx-model';
    export class TodosService {
      private model: Model<Todo[]>;
      todos$: Observable<Todo[]>;
      constructor(private modelFactory: ModelFactory<Todo[]>) {
        this.model = this.modelFactory.create([]); // create model and pass initial data
        this.todos$ =$; // expose model data as named public property
      toggleTodo(id: string) {
        // retrieve raw model data
        const todos = this.model.get();
        // mutate model data
        todos.forEach(t => {
          if ( === id) {
            t.done = !t.done;
        // set new model data (after mutation)
  4. Use service in your component. Import and inject service into components constructor. Subscribe to services data in template todosService.todos$ | async or explicitly this.todosService.todos$.subscribe(todos => { /* ... */ })

    import { Component, OnInit, OnDestroy } from '@angular/core';
    import { Subject } from 'rxjs';
    import { TodosService, Todo } from './todos.service';
      selector: 'ngx-model-todos',
      templateUrl: `
        /* ... */
        <h1>Todos ({{count}})</h1>
          <!-- template subscription to todos using async pipe -->
          <li *ngFor="let todo of todosService.todos$ | async" (click)="onTodoClick(todo)">
    export class TodosComponent implements OnInit, OnDestroy {
      private unsubscribe$: Subject<void> = new Subject<void>();
      count: number;
      constructor(public todosService: TodosService) {}
      ngOnInit() {
        // explicit subscription to todos to get count
            takeUntil(this.unsubscribe$) // declarative unsubscription
          .subscribe(todos => this.count = todos.length);
      ngOnDestroy(): void {
        // for declarative unsubscription
      onTodoClick(todo: Todo) {

Available Model Factories

Models are created using model factory as shown in above example this.model = this.modelFactory.create([]);. Multiple model factories are provided out of the box to support different use cases:

  • create(initialData: T): Model<T> - create basic model which is immutable by default (JSON cloning)
  • createMutable(initialData: T): Model<T> - create model with no immutability guarantees (you have to make sure that model consumers don't mutate and corrupt model state) but much more performance because whole cloning step is skipped
  • createMutableWithSharedSubscription(initialData: T): Model<T> - gain even more performance by skipping both immutability and sharing subscription between all consumers (eg situation in which many components are subscribed to single model)
  • createWithCustomClone(initialData: T, clone: (data: T) => T) - create immutable model by passing your custom clone function (JSON cloning doesn't support properties containing function or regex so custom cloning functionality might be needed)

Relationship to Angular Model Pattern

This is a library version of Angular Model Pattern. All the original examples and documentation are still valid. The only difference is that you can install ngx-model from npm instead of having to copy model pattern implementation to your project manually.

Check out the Blog Post and Advanced Usage Patterns for more how-tos and examples.

Getting started with Schematics

  1. make sure you're using this in project generated with Angular CLI.
  2. install dependency with npm i -D @angular-extensions/schematics
  3. generate model services with ng g @angular-extensions/schematics:model --name path/my-model
  4. or with ng g @angular-extensions/schematics:model --name path/my-model-collection --items form model of collection of items
  5. add your own model service methods and tests

Generating model using schematics

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npm i ngx-model

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  • tomastrajan