Answer:41

apps/forms/41-control-value-accessor/src/app/feedback-form/feedback-form.component.html

@@ -13,7 +13,7 @@
     [formControl]="feedbackForm.controls.email"
     placeholder="Email"
     type="email" />
-  <app-rating-control (ratingUpdated)="rating = $event"></app-rating-control>
+  <app-rating-control [formControl]="feedbackForm.controls.rating"></app-rating-control>
   <textarea
     class="feedback-form-control"
     [formControl]="feedbackForm.controls.comment"
@@ -22,7 +22,7 @@
     class="feedback-form-submit"
     type="submit"
     [disabled]="
-      !feedbackForm.touched || rating === null || feedbackForm.invalid
+      !feedbackForm.touched || feedbackForm.invalid
     ">
     Submit
   </button>

apps/forms/41-control-value-accessor/src/app/feedback-form/feedback-form.component.ts

@@ -26,14 +26,14 @@ export class FeedbackFormComponent {
       validators: Validators.required,
     }),
     comment: new FormControl(),
+    rating: new FormControl(null, {
+      validators: Validators.required,
+    }),
   });
 
-  rating: string | null = null;
-
   submitForm(): void {
     this.feedBackSubmit.emit({
       ...this.feedbackForm.value,
-      rating: this.rating,
     });
 
     this.feedbackForm.reset();

apps/forms/41-control-value-accessor/src/app/rating-control/rating-control.component.html

@@ -5,7 +5,7 @@
   </symbol>
 </svg>
 <div class="rating">
-  @for (item of [].constructor(5); track item) {
+  @for (item of [].constructor(5); track $index) {
     <svg
       class="star"
       [class.star-active]="isStarActive($index, value)"

apps/forms/41-control-value-accessor/src/app/rating-control/rating-control.component.ts

@@ -1,19 +1,37 @@
-import { Component, EventEmitter, Output } from '@angular/core';
+import { Component, forwardRef } from '@angular/core';
+import { ControlValueAccessor, NG_VALUE_ACCESSOR } from '@angular/forms';
 
 @Component({
   selector: 'app-rating-control',
   templateUrl: 'rating-control.component.html',
   styleUrls: ['rating-control.component.scss'],
+  providers: [
+    {
+      provide: NG_VALUE_ACCESSOR,
+      useExisting: forwardRef(() => RatingControlComponent),
+      multi: true,
+    },
+  ],
 })
-export class RatingControlComponent {
-  @Output()
-  readonly ratingUpdated: EventEmitter<string> = new EventEmitter<string>();
+export class RatingControlComponent implements ControlValueAccessor {
+  onChange: (value: number | null) => void = () => {};
+  onTouched: () => void = () => {};
 
   value: number | null = null;
 
+  writeValue(value: number | null): void {
+    this.value = value;
+  }
+  registerOnChange(fn: any): void {
+    this.onChange = fn;
+  }
+  registerOnTouched(fn: any): void {
+    this.onTouched = fn;
+  }
+
   setRating(index: number): void {
     this.value = index + 1;
-    this.ratingUpdated.emit(`${this.value}`);
+    this.onChange(this.value);
   }
 
   isStarActive(index: number, value: number | null): boolean {