Sharing Information: Passing Data Between Parent and Child Components in Angular 4

Question

Sharing Information: Passing Data Between Parent and Child Components in Angular 4

Whenever I attempt to transfer data from a parent component to a child component, I encounter an undefined message in the console. The data is presented as an array.

Parent Component HTML:

<div class="section welcome-section fp-section fp-table" *ngFor="let section of sections">
    <div class="fp-tableCell">
      <app-question-card [data]="section"></app-question-card>
    </div>
  </div>

Child Component TypeScript:

@Input() data;
  question = [];
  constructor() {
    this.question = this.data;
  }

  ngOnInit() {
    console.log(this.question); //returns undefined
  }

angular typescript

Answer 1

Answer №1

The task cannot be completed in the constructor because the value is not populated yet; it should be handled in the ngOnInit method, similar to how you are checking the value.

@Input() data;
question = [];

constructor() {
}

ngOnInit() {
  this.question = this.data;
  console.log(this.question);
}

Answer 2

The task cannot be completed in the constructor because the value is not populated yet; it should be handled in the ngOnInit method, similar to how you are checking the value.

@Input() data;
question = [];

constructor() {
}

ngOnInit() {
  this.question = this.data;
  console.log(this.question);
}

Answer 3

Answer №2

To achieve this functionality, you can utilize the Input() decorator as shown in the code snippet below:

parent.component.ts -

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

@Component({
  selector: 'app-parent',
  template: `
    <app-child [childMessage]="parentMessage"></app-child>
  `,
  styleUrls: ['./parent.component.css']
})
export class ParentComponent{
  parentMessage = "message from parent"
  constructor() { }
}

child.component.ts -

import { Component, Input } from '@angular/core';

@Component({
  selector: 'app-child',
  template: `
      Say {{ childMessage}}
  `,
  styleUrls: ['./child.component.css']
})
export class ChildComponent {

  @Input() childMessage: string;

  constructor() { }

}

For more details, check out this resource.

Answer 4

To achieve this functionality, you can utilize the Input() decorator as shown in the code snippet below:

parent.component.ts -

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

@Component({
  selector: 'app-parent',
  template: `
    <app-child [childMessage]="parentMessage"></app-child>
  `,
  styleUrls: ['./parent.component.css']
})
export class ParentComponent{
  parentMessage = "message from parent"
  constructor() { }
}

child.component.ts -

import { Component, Input } from '@angular/core';

@Component({
  selector: 'app-child',
  template: `
      Say {{ childMessage}}
  `,
  styleUrls: ['./child.component.css']
})
export class ChildComponent {

  @Input() childMessage: string;

  constructor() { }

}

For more details, check out this resource.

Answer 5

Answer №3

In the world of Angular Lifecycle, it is recommended to utilize the ngOnInit method specifically for setting initial input values.

@Input() data;

constructor() {
}

ngOnInit() {
  let question = this.data;
  console.log(this.question);
}

Answer 6

In the world of Angular Lifecycle, it is recommended to utilize the ngOnInit method specifically for setting initial input values.

@Input() data;

constructor() {
}

ngOnInit() {
  let question = this.data;
  console.log(this.question);
}

Answer 7

Answer №4

We have the ability to transfer data using Input()

Child.html

<app-chart [userData]='<< JSON OBJ | ANY VALUE WHICH YOU WANT TO TRANSFER >>'></app-chart>

chart.component.ts

@Input() userData: any = [];

ngOnInit() {
    console.log(this.userData); // utilize ngOnInit in Angular for setting input values
}

Answer 8

We have the ability to transfer data using Input()

Child.html

<app-chart [userData]='<< JSON OBJ | ANY VALUE WHICH YOU WANT TO TRANSFER >>'></app-chart>

chart.component.ts

@Input() userData: any = [];

ngOnInit() {
    console.log(this.userData); // utilize ngOnInit in Angular for setting input values
}

Sharing Information: Passing Data Between Parent and Child Components in Angular 4

Answer №1

Answer №2

Answer №3

Answer №4

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