How to check/uncheck a list of checkboxes in react

Question

I have a room page and in that page I have a list of sensors attached to that room, those sensors can be selected using a checkbox, like so:

<div className="checkboxRowContent">
  {sensors.map(s => {
    return (
      <div className="checkboxElementWrapper" key={s.id}>
        <label htmlFor={`sensor${s.id}`}>
          <div className="checkboxLabel">
            <Link to={`/sensors/edit/${s.id}`}>{s.name}</Link>
          </div>
          <input
            type="checkbox"
            id={`sensor${s.id}`}
            name="sensorId"
            value={s.id}
            checked={s.roomId === values.id}
            onChange={handleCheckbox}
          />
          <span className="checkbox" />
        </label>
      </div>
    );
  })}
</div>

the problem is - this approach prohibits me from unchecking the checkbox (so if in db that sensor is attached to that room - that's it). How could I rewrite this so that I can check/uncheck this checkbox?

Answer 1

in the class you must have state for that,

a sample would be somewhat like this

export default class yourComponent extends React.Component {

  state = {
    checkedBoxes: []
  }

  handleCheckbox = (e, s) => {
    const checkedBoxes = [...this.state.checkedBoxes];
    if(e.target.checked) {
      checkedBoxes.push(s)
    } else {
      const index = checkedBoxes.findIndex((ch) => ch.roomId === s.roomId);
      checkedBoxes.splice(index, 1);
    }
    this.setState({checkedBoxes});
  }


  render() {

    return(
      <div className="checkboxRowContent">
      {sensors.map(s => {
          return (
            <div className="checkboxElementWrapper" key={s.id}>
              <label htmlFor={`sensor${s.id}`}>
                <div className="checkboxLabel">
                  <Link to={`/sensors/edit/${s.id}`}>{s.name}</Link>
                </div>
                <input
                  type="checkbox"
                  id={`sensor${s.id}`}
                  name="sensorId"
                  checked={checkedBoxes.find((ch) => ch.roomId === s.roomId)}
                  onChange={(e) => handleCheckbox(e, s)}
                />
                <span className="checkbox" />
              </label>
            </div>
          );
        })}
      </div>
    )
  }
}

A state, checkedBoxes for getting all selected checkboxes.

A handler handleCheckbox for handling checkbox clicks,

Answer 2

You have handleCheckBox and a controlled component. We don't see what you do in the event handler but when it's controlled, you can check it by altering your sensors array (if in state/props) so s.roomId === values.id will be true.

If you don't want it to be controlled, you can probably use defaultChecked which will let you work with it in a different way.

see https://reactjs.org/docs/forms.html#controlled-components