angular/components

Radios should have separate unique selection in different form containers

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#5983 opened on Jul 23, 2017

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P4area: material/radiohelp wanted

Description

Bug, feature request, or proposal:

Bug

What is the expected behavior?

Radio group controls with the same name should not correlate with each other if they belong to different forms.

What is the current behavior?

If you change value in one radio group, then the value will be unset for all the other radio groups with the same name in other forms

What are the steps to reproduce?

<form>
  <md-radio-group ngModel="Winter" name="season">
    <md-radio-button *ngFor="let season of seasons" [value]="season">
      {{season}}
    </md-radio-button>
  </md-radio-group>
</form>

Second form:

<form>
  <md-radio-group ngModel="Summer" name="season">
    <md-radio-button *ngFor="let season of seasons" [value]="season">
      {{season}}
    </md-radio-button>
  </md-radio-group>
</form>

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What is the use-case or motivation for changing an existing behavior?

Currently it's impossible to implement a list (of similar items) if its items contain forms.

Which versions of Angular, Material, OS, TypeScript, browsers are affected?

@angular/cli: 1.2.0 node: 8.0.0 os: win32 x64 @angular/animations: 4.3.1 @angular/cdk: 2.0.0-beta.8 @angular/common: 4.3.1 @angular/compiler: 4.3.1 @angular/core: 4.3.1 @angular/forms: 4.3.1 @angular/http: 4.3.1 @angular/material: 2.0.0-beta.8 @angular/platform-browser: 4.3.1 @angular/platform-browser-dynamic: 4.3.1 @angular/platform-server: 4.3.1 @angular/router: 4.3.1 @angular/cli: 1.2.0 @angular/compiler-cli: 4.3.1 @angular/language-service: 4.3.1

Contributor guide

Tech stack
typescript
Domain
frontend
Issue type
bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
half day
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
stale
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
clear
Prerequisites
Angular basicsAngular MaterialAngular FormsTypeScript
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
60
Research direction
Investigate the md radio group and md radio button source files to understand how the name property is scoped. The issue suggests that radio groups with the same name across different forms interfere. Look at how Angular forms handle name uniqueness and consider if a form specific scope should be applied. Check the comments for any proposed solutions or related issues.