Angular Injecting Services

Overview

In Angular, Services are a type of class which provides functionality that can be shared across different components in an application. Services are used to separate the business logic from the presentation logic. It is a common pattern in Angular applications to use a service to fetch data from a back-end system.

Syntax

Following is the syntax for injecting services in an Angular application:

import { Component } from '@angular/core';
import { MyService } from './my-service';

@Component({
  selector: 'my-component',
  template: `...`,
  providers: [ MyService ]
})
export class MyComponent {
  constructor(private myService: MyService) {}
}

Example

Here is an example of how to use a service in an Angular component:

• Create a Service, 'MyService':

import { Injectable } from '@angular/core';

@Injectable({
  providedIn: 'root',
})
export class MyService {
  getServiceData(){
    return 'This is data from MyService';
  }
}

• Inject the Service in a Component:

import { Component } from '@angular/core';
import { MyService } from './my-service';

@Component({
  selector: 'my-component',
  template: `{{serviceData}}`
})
export class MyComponent {
  constructor(private myService: MyService) {}

  serviceData = this.myService.getServiceData();
}

Output

The output of the above component will be:

This is data from MyService

Explanation

In the above example, the MyService class is decorated with the @Injectable decorator to indicate that the class can be injected into other components or services. The providedIn property is set to 'root' to indicate that an instance of the service should be created for the root injector.

The MyComponent class injects the MyService class using the constructor. The private keyword is used to create a private variable myService that can be used in the component's template. In this example, serviceData property is defined that initializes the value of the property by calling the getServiceData() method of MyService class.

Use

In Angular applications, Services are often used to fetch data from a server, perform complex calculations or transformation on data, or handle user authentication. By separating the functionality into small reusable services, the overall development process becomes more efficient.

Important Points

• Services are used to provide functionality that can be shared across different components in an Angular application.
• Services can be injected into Components or other services using the Angular dependency injection system.
• The @Injectable decorator is used to indicate that a class can be injected as a service in an Angular application.
• The provider configuration option is used to register a service with the Angular dependency injection system.

Summary

In this tutorial, we learned the basics of injecting services in an Angular application. We saw how to create a service and how to inject it into a component using the Angular dependency injection system. We also saw an example of how to use the service in a component to get some data that can be used to display information in the template. By separating the business logic from the presentation logic, it becomes easier to manage the code and develop a more efficient and scalable application.