How to create a service in Angular?Example

Services are a fundamental part of Angular applications, enabling the encapsulation of reusable code and the separation of concerns. They offer a way to centralize business logic, data retrieval, and other functionalities that can be shared across multiple components. In this article, we will explore the process of creating a service in Angular, providing step-by-step guidance along with illustrative examples.

Step 1: Generating a Service

To create a service in Angular, you can take advantage of the Angular CLI (Command Line Interface) to generate the necessary files and boilerplate code. Open your terminal or command prompt, navigate to your project directory, and execute the following command:

syntax : ng generate service <service-name>

command promt
ng generate service ExampleService

This command generates a service file (ExampleService.service.ts) along with a corresponding unit test file.

Step 2: Implementing the Service

You have created the service in step 1, now we need to implement that service. Open the generated service file (ExampleService.service.ts) in your preferred code editor. Within the service class, you can define the desired functionality and business logic.

Example:

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

@Injectable({
  providedIn: 'root'
})
export class ExampleService {
  constructor() { }

  getData(): string {
    return 'This is data from the service';
  }
}

In this example, we have created an ExampleService class with a `getData()` method that returns a string representing data from the service.

Step 3: Providing the Service

To make the service accessible throughout your Angular application, you need to provide it at an appropriate level. Angular offers various options for providing services, depending on the desired scope.

a. Providing at the Root Level

By providing a service at the root level, you ensure that a single instance of the service is shared across the entire application.

Example:

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

@Injectable({
  providedIn: 'root'
})
export class ExampleService {
  // Service implementation
}

b. Providing at the Component Level

Alternatively, you can provide a service at the component level, creating a separate instance of the service for each component that injects it. This approach is useful when you want the service to have a specific scope limited to a component and its child components.

Example:

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

@Injectable()
export class ExampleService {
  // Service implementation
}

Step 4: Injecting the Service

To use the service in a component or another service, you need to inject it using Angular's dependency injection mechanism (you can check more about Depedency Injection here). Import the service and include it as a constructor parameter in the component or service where you wish to use it.

Example:

typescript
import { Component } from '@angular/core';
import { ExampleService } from './example.service';

@Component({
  selector: 'app-example',
  template: `
    <h1>{{ data }}</h1>
  `
})
export class ExampleComponent {
  data: string;

  constructor(private exampleService: ExampleService) {
    this.data = this.exampleService.getData();
  }
}

In this example, we inject the ExampleService into the ExampleComponent and utilize it to retrieve data within the component's constructor.

Conclusion:
Creating a service in Angular involves generating the necessary files, implementing the desired functionality, providing the service at the appropriate level, and injecting it into the components or services where it is required. Services are essential for encapsulating reusable code and promoting the separation of concerns in Angular applications. By following these steps and leveraging the power of services, you can build modular and maintainable Angular applications with ease.

Read more :

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2. Angular 16: Understanding Required Input Properties, Example

3. What is signals in Anglaur 16?Example

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5. Angular 16 & 17 — game changer or loss of identity?

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