Cross-component communication in Angular

Question

Cross-component communication in Angular

I'm currently developing a web-based application using angular version 6.

Within my application, there is a component that contains another component as its child. In the parent component, there is a specific function that I would like to invoke when a button in the child component is clicked.

To illustrate the structure of my components, please refer to this image:

https://i.stack.imgur.com/JFxAc.jpg

After some research, it seems that the solution lies with the use of the Angular @Output decorator. However, I am still having trouble implementing it effectively.

Here is how my code has been organized:

Parent Component - component.ts file

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

@Component({
  selector: 'app-teacher-home',
  templateUrl: './teacher-home.component.html',
  styleUrls: ['./teacher-home.component.scss']
})
export class TeacherHomeComponent implements OnInit {

  constructor() { }

  ngOnInit() {
  }

  formView: boolean = false;

  toggleForm(){
    this.formView = !this.formView;
  }
}

Parent component - component.html file

<div>
    <child-compnent></child-compnent>
</div>

Child component - component.html file

<div>
    <button>Toggle Form view</button>
</div>

I am seeking assistance on how to properly call the toggleForm() function from the parent component when the button in the child component is clicked.

javascript angular typescript components

Answer 1

Answer №1

Here's an interesting article you should read: Understanding @Output and EventEmitter in Angular

Let's take a look at the child component:

@Component({
  selector: 'app-child',
  template: `<button (click)="sendToParent('hi')" >sendToParent</button> `
})
export class AppChildComponent {
  @Output() childToParent = new EventEmitter;

  sendToParent(name){
    this.childToParent.emit(name);
  }
}

Now, let's move on to the parent component:

@Component({
  selector: 'my-app',
  templateUrl: './app.component.html',
  styleUrls: [ './app.component.css' ]
})
export class AppComponent  {
  toggle(){
    console.log('toggle')
  }

}

Here's the HTML code for the parent component:

<app-child (childToParent)="toggle($event)"></app-child>

If you want to see this implementation in action, check out the live DEMO.

Answer 2

Here's an interesting article you should read: Understanding @Output and EventEmitter in Angular

Let's take a look at the child component:

@Component({
  selector: 'app-child',
  template: `<button (click)="sendToParent('hi')" >sendToParent</button> `
})
export class AppChildComponent {
  @Output() childToParent = new EventEmitter;

  sendToParent(name){
    this.childToParent.emit(name);
  }
}

Now, let's move on to the parent component:

@Component({
  selector: 'my-app',
  templateUrl: './app.component.html',
  styleUrls: [ './app.component.css' ]
})
export class AppComponent  {
  toggle(){
    console.log('toggle')
  }

}

Here's the HTML code for the parent component:

<app-child (childToParent)="toggle($event)"></app-child>

If you want to see this implementation in action, check out the live DEMO.

Answer 3

Answer №2

Here are a couple of methods to accomplish this:

One option is to establish an event within the child component and assign it a callback function, similar to the following:
```
@Output('eventTrigger') buttonClicked = new EventEmitter();
```

Use buttonClicked.emit() to trigger the event when needed.

On the parent side, you can implement it like this:

<div>
    <child-component (eventTrigger)="performAction()"></child-component>
</div>

Alternatively, you can create a shared service that contains shared functions and data for both components.

Answer 4

Here are a couple of methods to accomplish this:

One option is to establish an event within the child component and assign it a callback function, similar to the following:
```
@Output('eventTrigger') buttonClicked = new EventEmitter();
```

Use buttonClicked.emit() to trigger the event when needed.

On the parent side, you can implement it like this:

<div>
    <child-component (eventTrigger)="performAction()"></child-component>
</div>

Alternatively, you can create a shared service that contains shared functions and data for both components.

Answer 5

Answer №3

To ensure proper functionality, you can utilize the @Output decorator within your child component and trigger an event when a button in the child component is clicked.

For example:

ChildComponent.html

<div>
    <button (click)="handleChildButtonClick()">Toggle Form View</button>
</div>

ChildComponent.ts

export class ChildComponent {
  @Output() toggleEvent: EventEmitter<any> = new EventEmitter<any>();

  ...
   handleChildButtonClick() {
     this.toggleEvent.emit(true);
   }
  ...
}

Parent Component

<div>
    <child-component (toggleEvent)="handleFormToggle()"></child-component>
</div>

Answer 6

To ensure proper functionality, you can utilize the @Output decorator within your child component and trigger an event when a button in the child component is clicked.

For example:

ChildComponent.html

<div>
    <button (click)="handleChildButtonClick()">Toggle Form View</button>
</div>

ChildComponent.ts

export class ChildComponent {
  @Output() toggleEvent: EventEmitter<any> = new EventEmitter<any>();

  ...
   handleChildButtonClick() {
     this.toggleEvent.emit(true);
   }
  ...
}

Parent Component

<div>
    <child-component (toggleEvent)="handleFormToggle()"></child-component>
</div>

Answer 7

Answer №4

One way to handle event listening in Angular is by utilizing the built-in EventEmitter.

app.component.ts

handleButtonClick($event) {}

app.component.html

<div>
    <child-compnent  (buttonClicked)="handleButtonClick($event)" ></child-compnent>
</div>

child.component.ts

@Output() buttonClicked: EventEmitter<any> = new EventEmitter<any>();

onButtonClick(){
  this.buttonClicked.emit('clicked');
}

Answer 8

One way to handle event listening in Angular is by utilizing the built-in EventEmitter.

app.component.ts

handleButtonClick($event) {}

app.component.html

<div>
    <child-compnent  (buttonClicked)="handleButtonClick($event)" ></child-compnent>
</div>

child.component.ts

@Output() buttonClicked: EventEmitter<any> = new EventEmitter<any>();

onButtonClick(){
  this.buttonClicked.emit('clicked');
}

Cross-component communication in Angular

Parent Component - component.ts file

Parent component - component.html file

Child component - component.html file

Answer №1

Answer №2

Answer №3

Answer №4

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