What is the best way to invoke a method in a child component from its parent, before the child component has been rendered?

Within my application, I have a parent component and a child component responsible for adding and updating tiles using a pop-up component. The "Add" button is located in the parent component, while the update functionality is in the child component. When there are no tiles (child component markup) to display, I need to add a tile without being able to access the child component's method openAddOrUpdatePopup().

Is there a way to call this method in the parent component without relying on the child component?

Here is a snippet of my code: - parent-html

<input type="button" class="btn" value="Add" (click)="applicationTile.openAddOrUpdatePopup()" />
<application-tile class="grid-item action-grid-item enable-events" *ngFor="let application of paginationParams.data" [ngClass]="{'active':activeApplication && activeApplication.applicationId == application.applicationId}" [application]="application"></application-tile>

parent.ts

export class ApplicationsComponent implements OnInit {
 @ViewChild (ApplicationTileComponent, {static: false}) applicationTile: ApplicationTileComponent ; 
}

Child.html

<label class="name">{{application.applicationName}}</label>
<div class="table-view">

<div class="table-view-row">
    <div>
        <label>Application value </label>
        <span>{{application.value ? application.value  : '-'}}</span>
    </div>
        <label>Application Version</label>
        <span>{{application.appVersion ? application.appVersion : '-'}}</span>
    </div>
    <ul class="actions">
        <li>
            <span class="icon svg-icon action-icon edit-icon" title="Edit" 
 (click)="openAddOrUpdatePopup(application, $event)"></span>
        </li>

    </ul>
</div>

<av-popup class="medium-popup" *ngIf="popupParams && popupParams.name == 'create-or-update-application'" [popupParams]="popupParams" (close)="popupParams = null">
<form name="form" (ngSubmit)="f.form.valid && popupParams.saveOrUpdateApplication()" #f="ngForm"></form></av-popup>

child.ts

 openAddOrUpdatePopup(application?, $event?) {
       if (application) {
        application = JSON.parse(JSON.stringify(application));
       }
       else {
        application = {
        applicationType: this.applicationTypes[0].applicationTypeVal
       }
     }

this.popupParams = {
  name: 'create-or-update-application',
  title: application.applicationId ? 'Edit ' + application.applicationName : "Create New Application",
  application: application
}

}

Answer №1

Could you provide more details on the question? Alternatively, could you share the code on StackBlitz and include the link?

There are several methods for establishing communication between parent and child components:

1. Utilizing Input & Output properties

2. Implementing a shared service with Observer pattern (Publish & Subscribe)

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