Overview

In many applications, data sharing between components is a common requirement. Angular provides several strategies and tools for sharing data efficiently and securely. In this chapter, we will explore various methods for sharing data in Angular and discuss best practices to ensure your applications are maintainable and performant.

1. Component Communication

Angular encourages the use of component-based architecture, where your application is divided into small, reusable components. To share data between these components, you have several options:

Input Properties (Data Down)

Use input properties to pass data from parent component to a child component. Child components can access these properties and use the data within their templates and logic.

// Parent Component
<app-child [data]="parentData"></app-child>

// Child Component
@Input() data: any;

Output Properties (Events Up)

To allow child components to communicate with parent components, you can use output properties to emit events when specific actions occur within the child component. Parent components can then subscribe to these events.

// Child Component
@Output() eventEmitter = new EventEmitter<any>();

// Parent Component
<app-child (eventEmitter)="handleEvent($event)"></app-child>

2. Services

Services are a crucial part of data sharing in Angular. They act as singletons, providing a way for components to communicate indirectly by sharing data through a common service.

3. State Management Libraries

Angular applications often benefit from state management libraries like NgRx and Akita. These libraries help manage complex application states by providing centralized stores, actions and reducers.

4. RxJS Observables

RxJS, a powerful library for reactive programming is widely used in Angular. Observables can be used to create asynchronous data streams that can be shared and consumed by various components.

5. Route Parameters

Data can also be shared through route parameters. Parameters in this route URL can be retrieved by components and used as input.