The Angular2 form field fails to toggle when using the @input variable

One of my Angular2 projects features a simple form:

Form.ts

import {Component, Input} from 'angular2/core'

@Component({
  selector: 'my-form',
  providers: [],
  template: `
    <form>

      {{ data }}

      <input type="text" placeholder="name" />
      <input *ngIf="data" type="text" placeholder="details" />
    </form>
  `,
  directives: []
})
export class MyForm {

  @Input() data: boolean;

  constructor() {

  }
}

Referencing this Plunkr example, I noticed that toggling the data @input via the button changes the text between true and false effortlessly.

However, the *ngIf directive doesn't seem to toggle the textfield as expected.

Any suggestions on what might be missing here?

App.ts

import {Component} from 'angular2/core'
import {MyForm} from './form'

@Component({
  selector: 'my-app',
  providers: [],
  template: `
    <div>
      <button (click)="toggle()">toggle details</button>
      <my-form data="{{visible}}"></my-form>
    </div>
  `,
  directives: [MyForm]
})
export class App {

  visible: boolean = false;

  constructor() {
    this.name = 'Angular2'
  }

  toggle() {
    this.visible = !this.visible;
  }
}

Answer №1

You might want to consider using the following code snippet:

<my-form [details]="visible"></my-form>

instead of

<my-form details="{{visible}}"></my-form>

This method allows for property binding, creating a one-way connection by reference. It ensures that any changes in the provided expression will be reflected in the sub component.

In your current implementation, you are simply initializing the input of the sub component with the value of the visible expression using interpolation. However, this means that the sub component won't receive updates.

Additionally, keep in mind that in your scenario, you are passing a string instead of a boolean. Only property binding supports providing data types other than strings...

Check out the functioning plunkr example: https://plnkr.co/edit/z7rKGb6mLdLNj2jtSlcU?p=preview.

Answer №2

Instead of using

<my-form [details]="visible"></my-form>

Check out this Plunker

<my-form details="{{visible}}"></my-form>

This code snippet passes the value as a string in quotes. Using [details] will pass the raw value without modification. Therefore, use the appropriate method based on the type of data you are passing.

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