angular-state-management

Angular State Management

Comprehensive guide to modern Angular state management patterns, from Signal-based local state to global stores and server state synchronization.

When to Use This Skill

• Setting up global state management in Angular
• Choosing between Signals, NgRx, or Akita
• Managing component-level stores
• Implementing optimistic updates
• Debugging state-related issues
• Migrating from legacy state patterns

Do Not Use This Skill When

• The task is unrelated to Angular state management
• You need React state management → use react-state-management

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Core Concepts

State Categories

Type	Description	Solutions
Local State	Component-specific, UI state	Signals, signal()
Shared State	Between related components	Signal services
Global State	App-wide, complex	NgRx, Akita, Elf
Server State	Remote data, caching	NgRx Query, RxAngular
URL State	Route parameters	ActivatedRoute
Form State	Input values, validation	Reactive Forms

Selection Criteria

Small app, simple state → Signal Services
Medium app, moderate state → Component Stores
Large app, complex state → NgRx Store
Heavy server interaction → NgRx Query + Signal Services
Real-time updates → RxAngular + Signals

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Quick Start: Signal-Based State

Pattern 1: Simple Signal Service

// services/counter.service.ts
import { Injectable, signal, computed } from "@angular/core";

@Injectable({ providedIn: "root" })
export class CounterService {
  // Private writable signals
  private _count = signal(0);

  // Public read-only
  readonly count = this._count.asReadonly();
  readonly doubled = computed(() => this._count() * 2);
  readonly isPositive = computed(() => this._count() > 0);

  increment() {
    this._count.update((v) => v + 1);
  }

  decrement() {
    this._count.update((v) => v - 1);
  }

  reset() {
    this._count.set(0);
  }
}

// Usage in component
@Component({
  template: `
    <p>Count: {{ counter.count() }}</p>
    <p>Doubled: {{ counter.doubled() }}</p>
    <button (click)="counter.increment()">+</button>
  `,
})
export class CounterComponent {
  counter = inject(CounterService);
}