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How to use Checkbox with Reactive Form in Angular?



In this post, we will learn reactive form with checkbox in angular. We will look at example of angular checkbox change event value. step by step explain angular checkbox list example. We will look at example of how to use checkbox in angular.

You can use reactive form with checkbox in angular 6, angular 7, angular 8 and angular 9 application.

In this example, i simply take website array variable with list of variable and display list of checkbox with website name. i also added on change event to get selected checkbox value for reactive form element. you can easily get all array of selected checkbox value on form submit.

So, let's follow bellow step to create simple example. you can also see bellow screen shot for checkbox in angular app.

Step 1: Import FormsModule

If you want to create form in angular app then you need to import FormsModule from @angular/forms library. so let's add following code to app.module.ts file.

src/app/app.module.ts

import { BrowserModule } from '@angular/platform-browser';

import { NgModule } from '@angular/core';

import { AppComponent } from './app.component';

import { FormsModule, ReactiveFormsModule } from '@angular/forms';

@NgModule({

declarations: [

AppComponent

],

imports: [

BrowserModule,

FormsModule,

ReactiveFormsModule

],

providers: [],

bootstrap: [AppComponent]

})

export class AppModule { }

Step 2: Form with ngModel

In this step, we will write code of html form with ngModel. so add following code to app.component.html file.

I used bootstrap class on this form. if you want to add than then follow this link too: Install Boorstrap 4 to Angular 9.

src/app/app.component.html

<div class="container">

<h1>Angular CheckBox Example - HDTuto.com</h1>

<form [formGroup]="form" (ngSubmit)="submit()">

<div class="form-group">

<label for="website">Website:</label>

<div *ngFor="let web of websiteList">

<label>

<input type="checkbox" [value]="web.id" (change)="onCheckboxChange($event)" />

{{web.name}}

</label>

</div>

</div>

<button class="btn btn-primary" type="submit" [disabled]="!form.valid">Submit</button>

</form>

</div>

Step 3: updated Ts File

In ts file. we will write submit() and get all input fields values. we need to import this libraries FormBuilder, FormGroup, FormControl, Validators, FormArray. so let's add following code to app.component.ts file.

src/app/app.component.ts

import { Component } from '@angular/core';

import { FormBuilder, FormGroup, FormControl, Validators, FormArray} from '@angular/forms';

@Component({

selector: 'app-root',

templateUrl: './app.component.html',

styleUrls: ['./app.component.css']

})

export class AppComponent {

form: FormGroup;

websiteList: any = [

{ id: 1, name: 'HDTuto.com' },

{ id: 2, name: 'HDTuto.com' },

{ id: 3, name: 'NiceSnippets.com' }

];

constructor(private formBuilder: FormBuilder) {

this.form = this.formBuilder.group({

website: this.formBuilder.array([], [Validators.required])

})

}

onCheckboxChange(e) {

const website: FormArray = this.form.get('website') as FormArray;

if (e.target.checked) {

website.push(new FormControl(e.target.value));

} else {

const index = website.controls.findIndex(x => x.value === e.target.value);

website.removeAt(index);

}

}

submit(){

console.log(this.form.value);

}

}

Now you can run your application using following command:

ng serve

You can check now.

I hope it can help you...




April 8, 2020 | Category : Angular



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