ReactJS: How to use boolean values in radio buttons?

Question

What is the proper way to use boolean data in radio buttons. The values will be converted from booleans to strings if used directly.

JSON-data for input fields that is preloaded:

var question = [
  {value: true, name: "Yes"},
  {value: false, name: "Not this time"}
]

The radio button fields:

<input type="radio" 
       name="question" 
       onChange={this.state.onRadioChange} 
       value={this.state.question[0].value} /> {this.state.question[0].name}
<input type="radio" 
       name="question" 
       onChange={this.state.onRadioChange} 
       value={this.state.question[1].value} /> {this.state.question[1].name}

The binding for onRadioChange:

onRadioChange: function(e) {
    console.log(e.target.value);
}

The console log displays that the selected values are converted from booleans to strings.

One way to handle this would be add an extra function to the onRadioChange function to convert "true"/"false" strings to booleans from e.target.value but its feels a bit hackery. Also, using just 'e.target.checked' won't work, because in some radio button groups I have other values than booleans (that needs to be passed through).

Some universal and clean solution would be to use constant values table that is transformed from and to REST.

Are there any special ReactJS way to do it? Maybe not.

Answer 1

Use the checked attribute of input for radio buttons. That attribute uses booleans.

Answer 2

In case that you are looking for a way to manage the radio button checked state with React, here you have an example:

var RadioButtons = React.createClass({
  getInitialState: function () {
    // Assuming there is always one option set to true.
    return {
      question: this.props.options.filter(function (option) {
        return option.value;
      })[0].name
    };
  },
  onRadioChange: function (e) {
    this.setState({
      question: e.target.value
    });
  },
  render: function () {
    var options = this.props.options.map(function (option, key) {
      return (
        <li key={key}>
          <input type="radio" 
             name="question" 
             onChange={this.onRadioChange} 
             checked={this.state.question === option.name}
             value={option.name} /> {option.name}
        </li>
      );
    }, this);
    return (
      <ul style={{listStyle: 'none'}}>
        {options}
      </ul>
    );
  }
});

This component can then be used passing your question list as properties:

<RadioButtons options={question} />

Check this fiddle.

Answer 3

The best solution to handle yes/no is a checkbox because you can use a boolean with the help of target.checked. If you want to use 2 radios instead unfortunately the simplest solution is to rely on strings.

You cannot use target.checked with radios (proposed in one of the answers) because it will always be true. If you click on the first radio, its target.checked inside handleChange() will be true, then if you click on the second radio its target.checked will also be true (e.g you'll never get false).

function handleChange(e) {
  const value = e.target.value;
  setState({answer: value});
}

<input
  type="radio"
  name="answer"
  onChange={handleChange}
  value="yes"
  checked={answer === "yes"}
/> Yes

<input
  type="radio"
  name="answer"
  onChange={handleChange}
  value="no"
  checked={answer === "no"}
/> Not this time

Full example: https://codesandbox.io/s/stack-overflow-34547733-nc04l

Answer 4

When working with binary (true or false valued) radio buttons in in React use a truthy and a falsy string for each input value and then in your handleChange function use either: Boolean(ev.target.value) or !!ev.target.value. This will convert whatever string you have in ev.target.value into boolean.

Example:

       <input
        type="radio"
        name="radioButtonField"  
        value="foo"    //a truthy string 
        onChange={(ev) =>
          setState((currentState) => ({
            ...currentState,
            [ev.target.name]: Boolean(ev.target.value),
          }))
        }
      />
      <input
        type="radio"
        name="radioButtonField"
        value=""       //a falsy string
        onChange={(ev) =>
          setState((currentState) => ({
            ...currentState,
            [ev.target.name]: Boolean(ev.target.value),
          }))
        }
      />