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

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