Angular 5 - Disabling Radio Buttons

There can be 2 solutions for this :-

1. Using the disabled attribute ([attr.disabled])

One solution to this problem can be using the disabled attribute ([attr.disabled]) instead of the disabled property ([disabled]), but [attr.disabled] works slightly differently, to enable the radio button you need to pass null to [attr.disabled] and any non-null value to disable it. Consider the below example :-

<input type="radio" name="enabled" [attr.disabled]="null" />Enabled1
<input type="radio" name="enabled" [attr.disabled]="null" />Enabled2

<input type="radio" name="disabled" [attr.disabled]="false" />Disabled1
<input type="radio" name="disabled" [attr.disabled]="false" />Disabled2

In this example the set of radio buttons named "enabled" will be enabled since for them [attr.disabled] is set to null, whereas the set of radio buttons named "disabled" will be disabled despite the [attr.disabled] being set to "false" this is because false is a non-null value.

2. Using fieldset tag

Another even better solution for this problem is using the <fieldset> tag for grouping the radio buttons together and then setting the [disabled] property on that <fieldset> tag instead of individual radio buttons. Below is an example for the same :-

<fieldset [disabled]=true>
    <input type="radio" name="test" />yes
    <input type="radio" name="test" />no
</fieldset>

Use this : (for reactive form approach)

 <input
    type="radio"
    id="primaryIPV6"
    value="2"
    [attr.disabled]="flagValue ? '' : null"
    formControlName="p_ip_type"
    (change)="optionalFn()">

Set flagValue programmatically from .ts class:

use -> null : false (null would be interpreted as false ) use -> true/'' : true (true or simply blank would be interpreted as true)

One way to deal with the problem is to place the disabled binding on the last radio button in the group. Here is a modified version of your code: http://plnkr.co/edit/v6S5G7Do5NAMKzZvNdcd?p=preview

<input type="radio" name="answer" value="Yes" [(ngModel)]="name" /> Yes
<input type="radio" name="answer" value="No" [(ngModel)]="name" [disabled]="isDisabled()" /> No

There is a bug and a design problem in disabling (using [disabled]) Angular template driven radio buttons.

I fixed the bug in this pull request: https://github.com/angular/angular/pull/20310

The design problem is that we put the [disabled] binding on a single radio button, but it's all the group that is affected by the data binding. Here is a modified version of your code that illustrate the problem: http://plnkr.co/edit/3yRCSPsdjXqhUuU9QEnc?p=preview

It works fine like this [attr.disabled]="isDisabledState === true"

And in the component class you can have isDisabledState: boolean = true

I ended up cheating. Instead of using the same name for both radio buttons, I gave each radio button a unique name and bound them to the same backing field. http://plnkr.co/edit/zNbODcAqZMgjXfluxhW6?p=preview

@Component({
  selector: 'my-app',
  template: `
    <form>
      Hello {{name}}!!!
      <input type="radio" name="answer1" value="Yes" [(ngModel)]="name" [disabled]="isDisabled1()" /> Yes
      <input type="radio" name="answer2" value="No" [(ngModel)]="name"  [disabled]="isDisabled2()" /> No
    </form>
  `,
})
export class App {
  name:string;
  isDisabled1(): boolean {
    return false;
  },
  isDisabled2(): boolean {
    return false;
  }
}

Since they are both bound to the same backing field, they end up being mutually exclusive, behaving the way radio buttons should. It also allows them to be independently disabled.

In my real-world scenario, I actually only did one-way binding with (click) events to set the bound value, but it's the same trick.

I was working with ionic and the following works for me.

<ion-radio class="fix-radio_button" *ngIf="!IsSuspended" color="default" [disabled]="q.QuestionOptionId==q.AnswerId" [checked]="q.QuestionOptionId==q.AnswerId"></ion-radio>

Considering DrNio answer you should use attr.disabled and set value as [value]="'Yes'". This is because assigning as "Yes" makes angular to evaluate it as an expression instead of just a value.So your input element would be :

<input type="radio" name="answer" [value]="'Yes'" [(ngModel)]="name"   [attr.disabled]="isDisabled()"  />

Here is your updated running code and punker..

Update Plunker

@Component({
  selector: 'my-app',
  template: `
    <form>
      Hello {{name}}!!!
      <input type="checkbox" name="dus" [(ngModel)]="isDisabled">
      <input type="radio" name="answer" value="Yes" [(ngModel)]="name" [disabled]="isDisabled" /> Yes
      <input type="radio" name="answer" value="NO" [(ngModel)]="name"  [disabled]="isDisabled" /> No
    </form>
  `,
})
export class App {
  name = 'Yes';;
  isDisabled = true;
}