retrieve information from Angular service

Question

retrieve information from Angular service

Is there a way for parent components to communicate with child components by injecting providers directly into the TypeScript file of each child component? I am trying to retrieve data using get and set methods, but I am unsure how to proceed. Any suggestions?

Service

export class ProductSharingDataService {

  public productName!: any;

  constructor() { }

  setRowName(selectedTableRowData: any){
    this.productName = selectedTableRowData;
  }

  getRowName(): string {
    return this.productName;
  }

}

components.ts

@Component({
          selector: 'app-product-page',
          templateUrl: './product-page.component.html',
          styleUrls: ['./product-page.component.css'],
          providers: [ProductSharingDataService] // Service injected here
        })
        export class ProductPageComponent {
        
          public selectedArrayParent!: Product;
        
          constructor(private productSharingDataService: 
                      ProductSharingDataService) {
            this.productSharingDataService.getRowName();  
            }
        
          receive($event: any) {
            this.selectedArrayParent = $event; 
// Trying to extract data from $event
          }
        
        }

angular typescript

Answer 1

Answer №1

There are a variety of methods to facilitate communication between a component parent and child:

NOTE: It is essential to specify the appropriate type instead of using 'any'.

1) Utilizing a service as a 'store':

service https://angular.io/guide/component-interaction#parent-and-children-communicate-using-a-service

export class ProductSharingDataService {

  private _productName!:any;

  set rowName(selectedTableRowData:any){
    this._productName = selectedTableRowData;
  }

  get rowName():string{
    return this._productName;
  }

  constructor() { }

}

parent

  constructor(private productSharingDataService: ProductSharingDataService) {
     this.productSharingDataService.rowName = 'Info (object, string, whatever...) you want to pass to the child';  
  }

child

name: any;

  constructor(private productSharingDataService: ProductSharingDataService) {
     this.name = this.productSharingDataService.rowName;
  }

2) Implementing @input() and @output: https://angular.io/guide/component-interaction

- Within the child component:

import { ..., EventEmitter, ..., Output } from '@angular/core';
...


 @Component({
      selector: 'app-child', ....



   @Input() varNameIn: any[] = []; 
    @Output() varNameOut: EventEmitter<any> 
      = new EventEmitter();
    ...

To send data to the parent component:

const infoToParent:any = 'Info (object, string, whatever...) you want to pass to the parent';
this.varNameOut.emit(info);

- Within the parent component:

HTML:

...
<app-child [varNameIn]="infoToChild" (varNameOut)="parentMethodToUseVarNameOutContent($event)"></app-child>
....

TypeScript:

    ...

    // Specify the same type for varNameOut as in the child:
    ...
    const infoToChild="Info (object, string, whatever...) you want to pass to the child";
    ...
    parentMethodToUseVarNameOutContent(varNameOut: any){
       console.log(varNameOut);
    }
    ...

Answer 2

There are a variety of methods to facilitate communication between a component parent and child:

NOTE: It is essential to specify the appropriate type instead of using 'any'.

1) Utilizing a service as a 'store':

service https://angular.io/guide/component-interaction#parent-and-children-communicate-using-a-service

export class ProductSharingDataService {

  private _productName!:any;

  set rowName(selectedTableRowData:any){
    this._productName = selectedTableRowData;
  }

  get rowName():string{
    return this._productName;
  }

  constructor() { }

}

parent

  constructor(private productSharingDataService: ProductSharingDataService) {
     this.productSharingDataService.rowName = 'Info (object, string, whatever...) you want to pass to the child';  
  }

child

name: any;

  constructor(private productSharingDataService: ProductSharingDataService) {
     this.name = this.productSharingDataService.rowName;
  }

2) Implementing @input() and @output: https://angular.io/guide/component-interaction

- Within the child component:

import { ..., EventEmitter, ..., Output } from '@angular/core';
...


 @Component({
      selector: 'app-child', ....



   @Input() varNameIn: any[] = []; 
    @Output() varNameOut: EventEmitter<any> 
      = new EventEmitter();
    ...

To send data to the parent component:

const infoToParent:any = 'Info (object, string, whatever...) you want to pass to the parent';
this.varNameOut.emit(info);

- Within the parent component:

HTML:

...
<app-child [varNameIn]="infoToChild" (varNameOut)="parentMethodToUseVarNameOutContent($event)"></app-child>
....

TypeScript:

    ...

    // Specify the same type for varNameOut as in the child:
    ...
    const infoToChild="Info (object, string, whatever...) you want to pass to the child";
    ...
    parentMethodToUseVarNameOutContent(varNameOut: any){
       console.log(varNameOut);
    }
    ...

Answer 3

Answer №2

Utilizing the @input() and @output decorator permits transferring data between components. The usage of the @output decorator in this method could potentially resolve your issue.

Within the recipient component (referred to as ProductPageParentComponent) TypeScript file, you must create a function to accept the value of the productName variable:

export class ProductPageParentComponent{

constructor() { }

productName: string;

receiveStringValue($event) {
  this.productName= $event;
 }
}

In the recipient component's HTML, include the following code:

<app-product-child-page (stringValueEvent)="receiveStringValue($event)"></app-product-child-page>
<h1>{{productName}}<h1>

In the sender component (known as ProductPageChildComponent) TypeScript file for the app-product-child-page selector, define a stringValueEvent variable with the @Output() decorator and assign it a new event emitter.

export class ProductPageChildComponent{

  productName: string;

  @Output() stringValueEvent = new EventEmitter<string>();

  constructor() { }

  ngOnInit(): void {
    this.productName= "Sample Product";
    this.stringValueEvent.emit(this.productName);
  }
}

Answer 4

Utilizing the @input() and @output decorator permits transferring data between components. The usage of the @output decorator in this method could potentially resolve your issue.

Within the recipient component (referred to as ProductPageParentComponent) TypeScript file, you must create a function to accept the value of the productName variable:

export class ProductPageParentComponent{

constructor() { }

productName: string;

receiveStringValue($event) {
  this.productName= $event;
 }
}

In the recipient component's HTML, include the following code:

<app-product-child-page (stringValueEvent)="receiveStringValue($event)"></app-product-child-page>
<h1>{{productName}}<h1>

In the sender component (known as ProductPageChildComponent) TypeScript file for the app-product-child-page selector, define a stringValueEvent variable with the @Output() decorator and assign it a new event emitter.

export class ProductPageChildComponent{

  productName: string;

  @Output() stringValueEvent = new EventEmitter<string>();

  constructor() { }

  ngOnInit(): void {
    this.productName= "Sample Product";
    this.stringValueEvent.emit(this.productName);
  }
}

retrieve information from Angular service

Answer №1

Answer №2

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