How to retrieve a component's property within an Angular2 provider?

Question

How to retrieve a component's property within an Angular2 provider?

As a beginner in OOP, I am currently experimenting with Ionic 2, Angular 2, and TypeScript. In my home.html file, I have an input field connected to the username property in home.ts as shown below:

export class HomePage {
public username: string;
public newusername: string; 
...
constructor(public users: UserService) {
...

My goal is to create a userService.ts service that will retrieve the username from the input field or home.ts, modify it, and save the result as newusername.

Do I need to create a constructor in the service/provider similar to the one in Homepage, which initializes a new object of Home even though I already created an object of this in home.ts?

Although I imported HomePage in userServices, I am unable to access newusername because I did not instantiate an object of it.

oop angular typescript ionic2

Answer 1

Answer №1

If you're unsure about what you need, take a look at this solution to see if it meets your requirements. (You can use newusername in the service itself)

NOTE: This solution does not involve Ionic2 as I am unfamiliar with it.

Working sample: https://plnkr.co/edit/03oXUTZYwRRo8PTfDFlA?p=preview

import { Component } from '@angular/core';
import {service} from './service';
@Component({
  selector: 'my-app',
  template: `
  New User : {{s.newusername}}<br>
  <input type="text" [(ngModel)]="username">
  <button (click)="click(username)">Add User</button>
  `
})
export class AppComponent { 

  constructor(private s:service){
  }

  click(username){
    this.s.addUserName(username);
    console.log(this.s.newusername)
  }

}

service.ts

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

@Injectable()
export class service{

  newusername:string;
  addUserName(str){
    this.newusername=str;
  }
}

Answer 2

If you're unsure about what you need, take a look at this solution to see if it meets your requirements. (You can use newusername in the service itself)

NOTE: This solution does not involve Ionic2 as I am unfamiliar with it.

Working sample: https://plnkr.co/edit/03oXUTZYwRRo8PTfDFlA?p=preview

import { Component } from '@angular/core';
import {service} from './service';
@Component({
  selector: 'my-app',
  template: `
  New User : {{s.newusername}}<br>
  <input type="text" [(ngModel)]="username">
  <button (click)="click(username)">Add User</button>
  `
})
export class AppComponent { 

  constructor(private s:service){
  }

  click(username){
    this.s.addUserName(username);
    console.log(this.s.newusername)
  }

}

service.ts

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

@Injectable()
export class service{

  newusername:string;
  addUserName(str){
    this.newusername=str;
  }
}

Answer 3

Answer №2

To implement this functionality, you have two options: either call a service from within the component's code or pass the component to the service.

constructor(public users: UserService) {}

@Input() public username: string;
// This function is called when an input changes
ngOnChanges() {
  this.newusername = this.users.convertUserName(this.username);
}

Alternatively, you can do the following:

constructor(public users: UserService) {
  users.component = this;
}

However, in both cases, you would still need a way to notify the service about any changes to the input, as shown in the example above.

Answer 4

To implement this functionality, you have two options: either call a service from within the component's code or pass the component to the service.

constructor(public users: UserService) {}

@Input() public username: string;
// This function is called when an input changes
ngOnChanges() {
  this.newusername = this.users.convertUserName(this.username);
}

Alternatively, you can do the following:

constructor(public users: UserService) {
  users.component = this;
}

However, in both cases, you would still need a way to notify the service about any changes to the input, as shown in the example above.

How to retrieve a component's property within an Angular2 provider?

Answer №1

Answer №2

Similar questions

Utilizing Angular's Dependency Injection to Provide Services to External Libraries

Why does the Angular page not load on the first visit, but loads successfully on subsequent visits and opens without any issues?

Having trouble accessing the theme in a styled component with @emotion/styled

Is there a way to convert my messages into different languages without relying on the 'translate' directive or pipe?

Ways to access a property within an object using TypeScript

Ensuring that a date is within a certain format in TypeScript

Issue with implementing JQuery datepicker within Angular 7 CLI application

What is the approach to constructing an observable that triggers numerous observables depending on the preceding outcome?

What is the best way to display a Nested JSON structure without an object key?

Storing data from a collection of interface objects in a string array

The preflight request in Angular2 is being rejected due to failing the access control check: The requested resource does not have the 'Access-Control-Allow-Origin' header

Angular and TypeScript make a powerful combination when working with the mat-table component

Implementing TypeScript inheritance by exporting classes and modules

Creating a stacked bar chart in Kendo UI Angular is a simple and effective way to visualize

Troubleshooting Puppeteer compatibility issues when using TypeScript and esModuleInterop

Ensure that the MUI icon color is set accurately

Is it planned to include StencilJS as a development choice in Ionic?

steps for retrieving final outcome from forkJoin

In Angular, there is an issue where the @ViewChild decorator does not reflect changes when the value of the child component is updated within the

No changes made to Observable when it's empty