Angular2 - Radio Button Binding

Solution 1:

use [value]="1" instead of value="1"

<input name="options" ng-control="options" type="radio" [value]="1"  [(ngModel)]="model.options" ><br/>

<input name="options" ng-control="options" type="radio" [value]="2" [(ngModel)]="model.options" ><br/>

Edit:

As suggested by thllbrg "For angular 2.1+ use [(ngModel)] instead of [(ng-model)] "

Solution 2:

Note - radio button binding is now a supported feature in RC4 onwards - see this answer

Radio button example using custom RadioControlValueAccessor similar to CheckboxControlValueAccessor (Updated with Angular 2 rc-1)

App.ts

import {Component} from "@angular/core";
import {FORM_DIRECTIVES} from "@angular/common";
import {RadioControlValueAccessor} from "./radio_value_accessor";
import {bootstrap} from '@angular/platform-browser-dynamic';

@Component({
    selector: "my-app",
    templateUrl: "template.html",
    directives: [FORM_DIRECTIVES, RadioControlValueAccessor]
})
export class App {

    model;

    constructor() {
        this.model = {
            sex: "female"
        };
    }
}

template.html

<div>
    <form action="">
        <input type="radio" [(ngModel)]="model.sex"  name="sex" value="male">Male<br>
        <input type="radio" [(ngModel)]="model.sex"  name="sex" value="female">Female
    </form>

    <input type="button" value="select male" (click)="model.sex='male'">
    <input type="button" value="select female" (click)="model.sex='female'">
    <div>Selected Radio: {{model.sex}}</div>
</div>

radio_value_accessor.ts

import {Directive, Renderer, ElementRef, forwardRef} from '@angular/core';
import {NG_VALUE_ACCESSOR, ControlValueAccessor} from '@angular/common';

export const RADIO_VALUE_ACCESSOR: any = {
    provide: NG_VALUE_ACCESSOR,
    useExisting: forwardRef(() => RadioControlValueAccessor),
    multi: true
};

@Directive({
   selector:
       'input[type=radio][ngControl],input[type=radio][ngFormControl],input[type=radio][ngModel]',
   host: {'(change)': 'onChange($event.target.value)', '(blur)': 'onTouched()'},
   bindings: [RADIO_VALUE_ACCESSOR]
})
export class RadioControlValueAccessor implements ControlValueAccessor {
   onChange = (_) => {};
   onTouched = () => {};

   constructor(private _renderer: Renderer, private _elementRef: ElementRef) {}

   writeValue(value: any): void {
       this._renderer.setElementProperty(this._elementRef.nativeElement, 'checked', value == this._elementRef.nativeElement.value);
   }
   registerOnChange(fn: (_: any) => {}): void { this.onChange = fn; }
   registerOnTouched(fn: () => {}): void { this.onTouched = fn; }
}

Source : https://github.com/angular2-school/angular2-radio-button

Plunker live demo : http://plnkr.co/edit/aggee6An1iHfwsqGoE3q?p=preview

Solution 3:

My manual workaround, which involves manually updating model.options when a new radio button is selected:

template: `
  <label *ngFor="let item of radioItems">
    <input type="radio" name="options" (click)="model.options = item" 
     [checked]="item === model.options">
    {{item}}
  </label>`

class App {
  radioItems = 'one two three'.split(' ');
  model      = { options: 'two' };
}

This Plunker demonstrates the above, as well as how to use a button to change the selected radio button -- i.e., to prove that the data binding is two-way:

<button (click)="model.options = 'one'">set one</button>

Solution 4:

Here is the best way to use radio buttons in Angular2. There is no need to use the (click) event or a RadioControlValueAccessor to change the binded property value, setting [checked] property does the trick.

<input name="options" type="radio" [(ngModel)]="model.options" [value]="1"
       [checked]="model.options==1" /><br/>
<input name="options" type="radio"  [(ngModel)]="model.options" [value]="2"
       [checked]="model.options==2" /><br/>

I published an example of using radio buttons: Angular 2: how to create radio buttons from enum and add two-way binding? It works from at least Angular 2 RC5.