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Hierarchical Injector and providers

In the world of Angular, Hierarchical Injector and providers play a pivotal role in managing dependencies, enabling modularization, and ensuring scalability within applications. Let’s delve into these concepts to comprehend their significance and implementation.

Understanding Hierarchical Injector:

Angular employs a Hierarchical Dependency Injection system, wherein each component has its dedicated injector. This hierarchical nature allows components to inherit dependencies from their parent components, ensuring encapsulation and modularity.

Providers in Angular

Providers are entities responsible for instantiating and managing dependencies within the Angular ecosystem. They specify how instances of services, components, or other objects are created and provided to the application.

Types of Providers:

  1. Class Providers:

    • They use classes as tokens to resolve dependencies, allowing the Hierarchical Injector to create instances of specified classes.
  2. Value Providers:

    • Value providers use literal values as tokens, allowing for direct assignment of specific values to dependencies.
  3. Factory Providers:

    • Factory providers utilize factory functions to create and provide instances of dependencies dynamically.
  4. Existing Providers:

    • They utilize instances of already existing dependencies rather than creating new instances.

Hierarchical Injector’s Role with Providers:

The Hierarchical Injector leverages providers to resolve and manage dependencies across an Angular application’s component tree. When a component requests a dependency, Angular’s Hierarchical Injector looks up its injector hierarchy to fulfill the request.

Benefits of Hierarchical Injectors and Providers:

  1. Modularity and Encapsulation:

    • Hierarchical Injectors ensure encapsulation of dependencies within components, enhancing modularity and maintainability.
  2. Scalability and Reusability:

    • Providers facilitate the creation of reusable services and components, enabling scalability across the application.
  3. Efficient Dependency Management:

    • The Hierarchical Injector efficiently manages dependencies, ensuring proper resolution and instantiation as required.

Best Practices:

  • Use providedIn Property: Leverage the providedIn property in service decorators to specify the module where the service should be provided. This promotes better organization and helps optimize the application.

  • Avoid Over-Providing: Be cautious not to over-provide services, as it might lead to unnecessary instances or conflicting dependencies within the application