[MdSelectionList] single selection (radio) option

Bug, feature request, or proposal:

Feature Request

What is the expected behavior?

The ability to specify whether or not the md-selection-list supports multiple value selection. I see a few different implementation options:

• Expose a multiple attribute on md-selection-list.
  • When present render each option as a checkbox, otherwise render as radio buttons.
  • This would be a breaking change as the current behavior is to use check boxes by default.
• Expose a type attribute on md-selection-list.
  • Possible values (for now) would include checkbox (default) and radio.
• Expose more specialized md-list-option components. ex md-list-radio-option.
  • Behavior of mixing checkbox and radio list options? Would probably be clunky.

What is the current behavior?

md-selection-list always renders each child md-list-option as a checkbox.

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

MdSelectionList is a good starting point for building generic Q&A style wizards/walkthroughs, but you are immediately limited in control over valid option selections. Having the ability to limit user selection to a single list option, presented using radio buttons, seems like it would be a reasonable extension of current behavior.

[gabriellupu]

As @Kyderman suggested, this would be the hacky way to achieve the radio-list behavior:

<mat-selection-list (selectionChange)="handleSelection($event)">
...
</mat-selection-list>

handleSelection(event) {
    if (event.option.selected) {
      event.source.deselectAll();
      event.option._setSelected(true);
    }
}

[homj]

I don’t understand, why this issue is labeled as “minor”. It’s a commonly used building block and shouldn’t be hard to implement.

I’d suggest a different implementation though: Multiple value selection by default and single selection on demand (via an attribute, e.g. single). This would be a non-breaking change (contrary to the suggested multiple attribute).