Скачать или смотреть How to Effectively Call a Method in Parent Component After ngOnInit of Child Component in Angular

Discover a clean solution to invoke a parent component method after the `ngOnInit` lifecycle hook of a child component in Angular. Learn how to use `EventEmitter` and `@ Output()` in your code.
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Calling a Method in Parent Component After ngOnInit of Child Component in Angular

When working with Angular, one common scenario developers encounter is the need to communicate between parent and child components. A frequent question is, "How can I call a method in the parent component after the ngOnInit lifecycle hook of a child component?" There are various approaches, but using EventEmitter and @ Output() is a clean and effective solution that ensures both components synchronize their actions without relying on less desirable methods like setTimeout().

The Problem

In your parent component, you might want to take action or trigger a function when a child component has finished its initialization process. The challenge is that during the ngOnInit() lifecycle hook of the child component, the parent isn't aware of when it's complete. Using a workaround like setTimeout() may seem to solve the problem, but it's not the best practice as it introduces unnecessary delays and potential bugs. Instead, we can use Angular's built-in event system.

The Solution: Using EventEmitter and @ Output()

The recommended approach to handle this scenario is to implement EventEmitter within the child component and make use of Angular's @ Output() decorator. This method allows the child to emit an event when it has fully initialized, which the parent can listen for and respond to accordingly.

Step-by-Step Implementation

Here’s how to set up your parent and child components effectively:

1. In the Child Component

In your child component, you will define an EventEmitter. This will emit an event when the component has finished its initialization:

[[See Video to Reveal this Text or Code Snippet]]

2. In the Parent Component

Now, in your parent component, you can define a method that will be called when the child component emits the event:

[[See Video to Reveal this Text or Code Snippet]]

3. Template Integration

Finally, you will connect the parent and child components in the parent’s template. Use (initializedEmitter) to bind the child component's emitted event to the childInit() method in the parent:

[[See Video to Reveal this Text or Code Snippet]]

Conclusion

Using EventEmitter with @ Output() is an effective way to establish communication between your Angular components. It allows the parent component to react whenever the child component completes its initialization without relying on potential pitfalls like setTimeout().

By following the outlined steps, you can ensure that your Angular applications remain clean and maintainable, improving the overall performance and readability of your code.

Feel free to explore this method further and improve your Angular component interactions!