Radio Group: Use Cases

Model value

The modelValue of a lion-radio-group is string equal to the choiceValue of the lion-radio element that has been checked.

Given the dinosaur example above, say that we were to select the last option (diplodocus).

Then the modelValue of the lion-radio-group will look as follows:

const groupElement = [parent].querySelector('lion-radio-group');
groupElement.modelValue;
  => "diplodocus";

The `name` attribute

The name attribute of a lion-radio-group automatically gets assigned to its lion-radio children. You can also specify names for the lion-radio elements, but if this name is different from the name assigned to lion-radio-group, then an exception will be thrown.

Our recommendation would be to set the name attribute only on the lion-radio-group and not on the lion-checkbox elements.

Pre-select

You can pre-select an option by adding the checked attribute to the selected lion-radio.

export const preSelect = () => html`
  <lion-radio-group name="dinos_2" label="What are your favourite dinosaurs?">
    <lion-radio label="allosaurus" .choiceValue=${'allosaurus'}></lion-radio>
    <lion-radio label="brontosaurus" .choiceValue=${'brontosaurus'} checked></lion-radio>
    <lion-radio label="diplodocus" .choiceValue=${'diplodocus'}></lion-radio>
  </lion-radio-group>
`;

Disabled

You can disable a specific lion-radio option by adding the disabled attribute.

export const disabledRadio = () => html`
  <lion-radio-group name="dinos_4" label="What are your favourite dinosaurs?">
    <lion-radio label="allosaurus" .choiceValue=${'allosaurus'}></lion-radio>
    <lion-radio label="brontosaurus" .choiceValue=${'brontosaurus'} disabled></lion-radio>
    <lion-radio label="diplodocus" .choiceValue=${'diplodocus'}></lion-radio>
  </lion-radio-group>
`;

You can do the same thing for the entire group by setting the disabled attribute on the lion-radio-group element.

export const disabledGroup = () => html`
  <lion-radio-group name="dinos_6" label="What are your favourite dinosaurs?" disabled>
    <lion-radio label="allosaurus" .choiceValue=${'allosaurus'}></lion-radio>
    <lion-radio label="brontosaurus" .choiceValue=${'brontosaurus'}></lion-radio>
    <lion-radio label="diplodocus" .choiceValue=${'diplodocus'}></lion-radio>
  </lion-radio-group>
`;

Label

You can use slot="label" instead of the label attribute for defining more complex labels, such as containing screen reader only text or an anchor.

export const label = () => html`
  <lion-radio-group name="dinos_7" label="Favourite dinosaur">
    <lion-radio .choiceValue=${'allosaurus'}>
      <label slot="label"
        ><a href="https://wikipedia.org/wiki/allosaurus" target="_blank">allosaurus</a></label
      >
    </lion-radio>
    <lion-radio .choiceValue=${'brontosaurus'}>
      <label slot="label"
        ><a href="https://wikipedia.org/wiki/brontosaurus" target="_blank">brontosaurus</a></label
      >
    </lion-radio>
    <lion-radio .choiceValue=${'diplodocus'}>
      <label slot="label"
        ><a href="https://wikipedia.org/wiki/diplodocus" target="_blank">diplodocus</a></label
      >
    </lion-radio>
  </lion-radio-group>
`;

Help text

You can add help text on each checkbox with help-text attribute on the <lion-radio>.

export const helpText = () => html`
  <lion-radio-group name="dinosTwo" label="Favourite dinosaur">
    <lion-radio
      label="allosaurus"
      .choiceValue=${'allosaurus'}
      help-text="Allosaurus is a genus of carnivorous theropod dinosaur that lived 155 to 145 million years ago during the late Jurassic period"
    ></lion-radio>
    <lion-radio
      label="brontosaurus"
      .choiceValue=${'brontosaurus'}
      help-text="Brontosaurus is a genus of gigantic quadruped sauropod dinosaurs"
    ></lion-radio>
    <lion-radio
      label="diplodocus"
      .choiceValue=${'diplodocus'}
      help-text="Diplodocus is a genus of diplodocid sauropod dinosaurs whose fossils were first discovered in 1877 by S. W. Williston"
    ></lion-radio>
  </lion-radio-group>
`;

Event

You can listen to the model-value-changed event whenever the value of the radio group is changed.

export const event = ({ shadowRoot }) => html`
  <lion-radio-group
    name="dinosTwo"
    label="Favourite dinosaur"
    @model-value-changed=${ev =>
      (ev.target.parentElement.querySelector('#selectedDinosaur').innerText = ev.target.modelValue)}
  >
    <lion-radio label="allosaurus" .choiceValue=${'allosaurus'}></lion-radio>
    <lion-radio label="brontosaurus" .choiceValue=${'brontosaurus'}></lion-radio>
    <lion-radio label="diplodocus" .choiceValue=${'diplodocus'}></lion-radio>
  </lion-radio-group>
  <br />
  <span>Selected dinosaur: <strong id="selectedDinosaur">N/A</strong></span>
`;

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