How to Validate Angular 2 FormArray for length and Regex - angular2-forms

Question

app.component.ts
import { Component,OnInit } from '#angular/core';
import {FormControl,FormGroup,FormArray,FormBuilder} from '#angular/forms'
#Component({
selector: 'my-app',
templateUrl: './app.component.html',
styleUrls: [ './app.component.css' ]
})
export class AppComponent {
name = 'Angular 6';
form=new FormGroup({
topics:new FormArray([])
})
addTopic(topic:HTMLInputElement){
(this.form.get('topics') as FormArray).push(new FormControl(topic.value));
topic.value='';
}
}
app.component.html
<form>
<input type="text" class="form-control" (keyup.enter)="this.addTopic(topic)" #topic />
<ul class="list-group">
<li class="list-group-item" *ngFor="let topic of form.get('topics').controls">
{{topic.value}}
</li>
</ul>
</form>
I have created a Multi Input Control using Angular FormArray but how can i Validate the same for Minimum 2 Items(Length=2) and only accept integer values.
How to Add Validators.minlength like Reactive Form / Model Driven Form Approach.
How can i get those items using ngModel?

Answer 1

I hope this helps.
import {
Component,
OnInit
} from '#angular/core';
import {
FormControl,
FormGroup,
FormArray,
FormBuilder
} from '#angular/forms'
#Component({
selector: 'my-app',
templateUrl: './app.component.html',
styleUrls: ['./app.component.css']
})
export class AppComponent {
name = 'Angular 6';
form = new FormGroup({
topics: new FormArray(this.formBuilder.control(''), [Validators.reqired, Valiadtors.minlength(2)], Validators.Paterrn("^[0-9]*$"))
])
addTopic(topic: HTMLInputElement) {
(this.form.get('topics') as FormArray).push(new FormControl(topic.value));
topic.value = '';
}
}