Angular call child component method from parent component

Question

I have a parent component having three instances of child component inside it.

child-product-detail.component.html

<form id="frmProduct" #frmProduct="ngForm" (ngSubmit)="onSave(frmProduct)">
   <ng-content select="[buttons-view]"></ng-content>
   <input type="text" id="txtProductName" name="txtProductName" [(ngModel)]="product.productName" />
</form>

child-product-detail.component.ts

onSave(form) {
    let isValid = this.validate(form);
    if (!isValid) return;
}

parent-product.compoment.html

<child-product-detail [product]="products[0]">
   <div buttons-view>
       <button type="button" class="btn" (click)="saveProduct(0)" >Save</button>                                    
   </div>
</child-product-detail>
<child-product-detail [product]="products[1]">
   <div buttons-view>
       <button type="button" class="btn" (click)="saveProduct(1)" >Save</button>                                    
   </div>
</child-product-detail>
<child-product-detail [product]="products[2]">
   <div buttons-view>
       <button type="button" class="btn" (click)="saveProduct(2)" >Save</button>                                    
   </div>
</child-product-detail>

parent-product.component.ts

saveProduct(productId) {
    let productToSave = this.products(productIndex);
    // Code required to call onSave method of child component
}

Is there anyway I can call onSave method of the child component passing the form object of it?

Thanks.

Answer 1

You can use the ViewChildren decorator.

@ViewChildren(ChildProductDetailComponent)
childComponents: QueryList<ChildProductDetailComponent>;

saveProduct(productId) {
   this.childComponents.get(productIndex).onSave();
}

Answer 2

You can use an eventemitter.

Assuming you have the child component with an output event function like this:

<app-product-stock (outputStockEvent)="outputStockEvent($event)"></app-product-stock>

Then this would be the function in the parent:

public outputStockEvent(event){
    this.stock = event
  }

and in the child component:

    constructor(private fb: FormBuilder) {
        this.stockForm = this.fb.group({
          a: '',
          b: '',
          c:'',
        });
       }

.....
 

    ngOnInit(): void {
        this.stockForm.valueChanges.subscribe(data =>{
          this.outputStockEvent.emit(data)
        })
      }

If you then use a "Save" button in the ParentComponent, you can write the values into a final array:

public save(){
  let finalObj ={ "stock":this.stock"}
}

Answer 3

Yes, you can do it using the @Output directive to emit custom events.

For example:

child-product-detail.component.ts

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

export class ChildProductDetailComponent {
    @Output() yourEventEmitter = new EventEmitter<any>();

    onSave(form) {
        let isValid = this.validate(form);
        if (isValid) {
            this.yourEventEmitter.emit(form)
        };
    }

When onSave() is executed, it emit the yourEventEmitter

parent-product.compoment.html

<child-product-detail (yourEventEmitter)="saveProduct($event)">
    <button type="button" class="btn" (click)="onSave(0)" >Save</button>
</child-product-detail>

Than the parent component got the event and run the function saveProduct() and receiving the form by the $event.

parent-product.component.ts

saveProduct(productId) {
    // the productId is the form from the child component
}

You cand learn more about it https://angular.io/api/core/EventEmitter