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Angular 2 Radio Button and Checkbox Example

By Arvind Rai, June 06, 2017
This page will walk through Angular 2 radio button and checkbox example. We will provide demo using template-driven form and reactive form. Using both type of form we will see how to create radio button and checkbox, fetch values and set them checked and validate them. Validation of radio button means at least one option must be checked and validation of checkbox means checkbox must be checked. We will create two separate components, one for template-driven form and another for reactive form in our application. Template-driven approach uses NgForm and NgModel directive. Reactive form uses FormGroup and FormControl classes to handle form elements. Now let us discuss complete example step by step.

Technologies Used

Find the technologies being used in our example.
1. Angular 4.0.0
2. TypeScript 2.2.0
3. Node.js 6.10.1
4. Angular CLI 1.0.4
5. Angular Compiler CLI 4.0.0

Project Structure

Find the project structure of our example.
angular-demo
|
|--src
|   |
|   |--app 
|   |   |
|   |   |--domain
|   |   |    | 
|   |   |    |--user.ts
|   |   |
|   |   |--services
|   |   |    | 
|   |   |    |--user-service.ts
|   |   |
|   |   |--template-driven-form.component.ts
|   |   |--reactive-form.component.ts
|   |   |--template-driven-form.component.html
|   |   |--reactive-form.component.html
|   |   |--style.css
|   |   |
|   |   |--app.component.ts
|   |   |--app.module.ts 
|   | 
|   |--main.ts
|   |--index.html
|   |--styles.css
|
|--node_modules
|--package.json 

Using Template-Driven Form

We will use template-driven from to create radio button and checkbox here. To work with template-driven from we need to use NgForm and NgModel directive. To enable it in our application we need to configure FormsModule in our application module.
Now we will create radio button and checkbox using template-driven from. We will see how to fetch values and validate them. Suppose we have a class whose fields will be populated by the form elements.
export class User { 
    userName: string;
    gender: string;
    isMarried: boolean = false;
    isTCAccepted: boolean;
    constructor() {
    }
} 

1. Creating Radio Button and Checkbox

We need to use ngModel as an attribute in radio button and checkbox so that they can be registered with NgForm directive.
Create button
<input type="radio" value="male" name="gender" ngModel> Male
<input type="radio" value="female" name="gender" ngModel> Female
Create checkbox
<input type="checkbox" name="tc" ngModel>

2. Fetch Value on Form Submit

When we submit the form and suppose the form value is stored in the instance of NgForm as form then we can fetch radio button and checkbox value using form.controls[...] as given below.
this.user.gender = form.controls['gender'].value;
this.user.isTCAccepted = form.controls['tc'].value; 
Where gender is the radio button name and tc is the checkbox name.

3. Set Radio Button and Checkbox Checked

To set radio button and checkbox checked we need to use property binding. Find the code.
<p>
   <input type="radio" value="male" name="gender" [ngModel]="user.gender" > Male
   <input type="radio" value="female" name="gender" [ngModel]="user.gender" > Female
</p>
<p>
   <input type="checkbox" name="tc" [ngModel]="user.isTCAccepted" >
</p> 
If user.gender has value as male then that radio button will be checked. For the checkbox if user.isTCAccepted has value as true then checkbox will be checked.

4. Validation

Suppose we want required validation with radio button.
<p>
   <input type="radio" value="male" name="gender" required #gender="ngModel"> Male
   <input type="radio" value="female" name="gender"required #gender="ngModel"> Female
</p> 
If we don't select any radio button then form will not be valid. To show validation message we can use local template variable.
<div *ngIf="gender.invalid"> 
    Gender required. 
</div> 
Now suppose we want required validation with checkbox.
<p>
   <input type="checkbox" name="tc" required #tc="ngModel">
</p> 
If checkbox has not been checked then the form will be invalid. To show validation message we can use local template variable.
<div *ngIf="tc.invalid> 
     Accept T & C.
</div> 

Using Reactive Form

We will use reactive form to create radio button and checkbox here. We will provide how to use them, set default value and validate them. In reactive form we need to use FormGroup and FormControl from @angular/forms library. To enable reactive form in our application, we need to configure ReactiveFormsModule in our application module.

1. Creating Radio Button and Checkbox

To create radio button and checkbox we will create an instance of FormGroup that will have properties of FormControl.
userForm = new FormGroup({
   gender: new FormControl(),
   tc: new FormControl()
}); 
Now in HTML template we need to use formControlName to map form elements.
<form [formGroup]="userForm" (ngSubmit)="onFormSubmit()">
  <p>
     <input type="radio" value="male" formControlName="gender"> Male
     <input type="radio" value="female" formControlName="gender"> Female
  </p>
  <p>
     <input type="checkbox" formControlName="tc">
  </p>
</form> 

2. Fetch Value on Form Submit

When form is submitted, we can fetch radio button and checkbox values using FormGroup instance, for example userForm. To fetch values we need to call get() method of FormGroup and pass the name of form control to this method as follows.
this.user.gender = this.userForm.get('gender').value;
this.user.isTCAccepted = this.userForm.get('tc').value; 

3. Set Radio Button and Checkbox Checked

To set a value in radio button and checkbox, we can use two methods of FormGroup.
setValue(): It sets values to all form controls.
patchValue(): It sets values to selected form controls.

For the example we are using patchValue() here.
setDefaultValues() {
   this.userForm.patchValue({gender:'male', tc:true});
}
When we call the above method, radio button will be checked with value male and checkbox will also be checked.

4. Validation

To validate radio button and checkbox, we need to use Validators from @angular/forms library. It is used while instantiating FormGroup.
userForm = new FormGroup({
   gender: new FormControl('', Validators.required),
   tc: new FormControl('', Validators.required)
}); 
In the above code snippet we are using Validators.required. It means if we do not select any radio button or checkbox is not checked then form will not be valid. To display validation message in HTML template, we can write code as follows.
<div *ngIf="userForm.get('gender').invalid"> 
	 Gender required. 
</div>		
<div *ngIf="userForm.get('tc').invalid"> 
         Accept T & C.
</div> 

Complete Example

user.ts
export class User { 
        userName: string;
	gender: string;
	isMarried: boolean = false;
	isTCAccepted: boolean;
        constructor() {
        }
}
user-service.ts
import { Injectable } from '@angular/core';

import { User } from '../domain/user';

@Injectable()
export class UserService {
   createUser(user: User) {
           //Log user data in console
           console.log("User Name: " + user.userName);
	   console.log("Gender: " + user.gender);
	   console.log("Married?: " + user.isMarried);
	   console.log("T & C accepted?: " + user.isTCAccepted);
   }   
}
template-driven-form.component.ts
import { Component, OnInit } from '@angular/core';
import { NgForm } from '@angular/forms';

import { UserService } from './services/user-service';
import { User } from './domain/user';

@Component({
   selector: 'app-template',
   templateUrl: './template-driven-form.component.html',
   styleUrls: ['./style.css'] 
})
export class TemplateDrivenFormComponent { 
        isValidFormSubmitted = false;
	user = new User();
	constructor(private userService: UserService) {
	}
	onFormSubmit(form: NgForm) {
	   this.isValidFormSubmitted = false;
	   if(form.invalid){
		  return;	
	   } 	
	   this.isValidFormSubmitted = true;
	   this.user.userName = form.controls['uname'].value;
	   this.user.gender = form.controls['gender'].value;
	   this.user.isMarried = form.controls['married'].value;
	   this.user.isTCAccepted = form.controls['tc'].value;
	   this.userService.createUser(this.user);
	   this.resetForm(form);
	}
	resetForm(form: NgForm) {
	   form.resetForm({
		   married: false
	   }); 
	}
	setDefaultValues() {
	   this.user.userName = 'Krishna';
	   this.user.gender = 'male';
	   this.user.isMarried = true;
	   this.user.isTCAccepted = false;
	}
} 
template-driven-form.component.html
<h3>Template Driven Form</h3>
<p *ngIf="isValidFormSubmitted" [ngClass] = "'success'">
    Form submitted successfully.
</p>
<form #userForm="ngForm" (ngSubmit)="onFormSubmit(userForm)">
  <table>
	 <tr> 
	   <td>Name:</td>
	   <td> 
	           <input name="uname" [ngModel]="user.userName" required #uname="ngModel">
		   <div *ngIf="uname.invalid && userForm.submitted && !isValidFormSubmitted" [ngClass] = "'error'"> 
			  Name required. 
		   </div>
	   </td>
	 </tr> 
	 <tr>
	    <td>Gender:</td>
	    <td> 
	         <input type="radio" value="male" name="gender" [ngModel]="user.gender" required #gender="ngModel"> Male
                 <input type="radio" value="female" name="gender" [ngModel]="user.gender" required #gender="ngModel"> Female
		 <div *ngIf="gender.invalid && userForm.submitted && !isValidFormSubmitted" [ngClass] = "'error'"> 
			  Gender required. 
		 </div>
	    </td> 
	 </tr>	  
	 <tr>
	  <td>Are you married? </td>
	  <td>
	   <input type="checkbox" name="married" [ngModel]="user.isMarried">
	  </td>
	 </tr>	 
	 <tr>
	  <td>Accept T & C </td>
	  <td>
	         <input type="checkbox" name="tc" [ngModel]="user.isTCAccepted" required #tc="ngModel">
		 <div *ngIf="tc.invalid && userForm.submitted && !isValidFormSubmitted" [ngClass] = "'error'"> 
		     Accept T & C.
		 </div>
	  </td>
	 </tr>		 
	 <tr> 	  
	   <td colspan="2">
	          <button>Submit</button>
		  <button type="button" (click)="setDefaultValues()">Set Default</button>
		  <button type="button" (click)="resetForm(userForm)">Reset</button>		  
	   </td>
	 </tr>	   
  </table>  
</form> 
style.css
table {
    border-collapse: collapse;
}
table, th, td {
    border: 1px solid black;
}
.error {
    color: red;
}
.success {
    color: green;
} 
reactive-form.component.ts
import { Component, OnInit } from '@angular/core';
import { FormControl, FormGroup, Validators } from '@angular/forms';

import { UserService } from './services/user-service';
import { User } from './domain/user';

@Component({
   selector: 'app-reactive',
   templateUrl: './reactive-form.component.html',
   styleUrls: ['./style.css'] 
})
export class ReactiveFormComponent { 
        isValidFormSubmitted: boolean = null;
	userForm = new FormGroup({
	   uname: new FormControl('', Validators.required),
	   gender: new FormControl('', Validators.required),
	   married: new FormControl(false),
	   tc: new FormControl('', Validators.required)
	});
	user = new User();
	constructor(private userService: UserService) {
	}	
        onFormSubmit() {
	   this.isValidFormSubmitted = false;
	   if(this.userForm.invalid){
		return;	
	   } 	
	   this.isValidFormSubmitted = true;	
	   console.log(this.userForm.valid);
	   this.user.userName = this.userForm.get('uname').value;
	   this.user.gender = this.userForm.get('gender').value;
	   this.user.isMarried = this.userForm.get('married').value;
	   this.user.isTCAccepted = this.userForm.get('tc').value;
	   this.userService.createUser(this.user);	 
	   this.reset();
	}
	reset() {
	   this.userForm.reset({
		    married: false
	   });	   
	}	
	setDefaultValues() {
	   this.userForm.patchValue({uname: 'Krishna', gender:'male', married:true});
	}	
} 
reactive-form.component.html
<h3>Reactive Form</h3>
<p *ngIf="isValidFormSubmitted && userForm.pristine" [ngClass] = "'success'">
    Form submitted successfully.
</p>
<form [formGroup]="userForm" (ngSubmit)="onFormSubmit()">
  <table>
	 <tr> 
	   <td>Name:</td>
	   <td> 
	           <input formControlName="uname">
		   <div *ngIf="userForm.get('uname').invalid && isValidFormSubmitted != null && !isValidFormSubmitted" [ngClass] = "'error'"> 
			  Name required. 
		   </div>
	   </td>
	 </tr> 
	 <tr>
	    <td>Gender:</td>
	    <td> 
	         <input type="radio" value="male" formControlName="gender"> Male
                 <input type="radio" value="female" formControlName="gender"> Female
		 <div *ngIf="userForm.get('gender').invalid && isValidFormSubmitted != null && !isValidFormSubmitted" [ngClass] = "'error'"> 
			  Gender required. 
		 </div>		 
	    </td> 
	 </tr>	  
	 <tr>
	   <td>Are you married? </td>
	   <td>
	     <input type="checkbox" formControlName="married">
	   </td>
	 </tr>	 
	 <tr>
	  <td>Accept T & C </td>
	  <td>
	         <input type="checkbox" formControlName="tc">
		 <div *ngIf="userForm.get('tc').invalid && isValidFormSubmitted != null && !isValidFormSubmitted" [ngClass] = "'error'"> 
		     Accept T & C.
		 </div>		 
	  </td>
	 </tr>		 
	 <tr> 	  
	   <td colspan="2">
	          <button>Submit</button>
		  <button type="button" (click)="setDefaultValues()">Set Default</button>
		  <button type="button" (click)="reset()">Reset</button>		  
	   </td>
	 </tr>	   
  </table>  
</form> 
app.component.ts
import { Component } from '@angular/core';

@Component({
   selector: 'app-root',
   template: `
		<app-template></app-template>
		<app-reactive></app-reactive>				
             `
})
export class AppComponent { 
} 
app.module.ts
import { NgModule } from '@angular/core';
import { BrowserModule } from '@angular/platform-browser';
import { FormsModule, ReactiveFormsModule } from '@angular/forms';

import { AppComponent }  from './app.component';
import { TemplateDrivenFormComponent }  from './template-driven-form.component';
import { ReactiveFormComponent }  from './reactive-form.component';
import { UserService } from './services/user-service';

@NgModule({
  imports: [     
        BrowserModule,
	FormsModule, 
	ReactiveFormsModule
  ],
  declarations: [
        AppComponent,
	TemplateDrivenFormComponent,
	ReactiveFormComponent
  ],
  providers: [
        UserService
  ],
  bootstrap: [
        AppComponent
  ]
})
export class AppModule { } 

Run Application

To run the application, find following steps.
1. Download source code using download link given on this page.
2. In your angular CLI application, replace src folder from the downloaded one.
3. Run ng serve using command prompt.
4. Now access the URL http://localhost:4200 . Find the print screen.
Angular 2 Radio Button and Checkbox Example

References

RadioControlValueAccessor
CheckboxControlValueAccessor
Angular 2 NgForm with NgModel Directive Example
Angular 2 FormGroup Example

Download Source Code

POSTED BY
ARVIND RAI
ARVIND RAI
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