问子组件的道具在父组件以空开始时不会更新

EN

// 1 - Parent - Wrong
render() {
const { record } = this.state;
if (!record) { return null; }
return (
  <div>
    <p>Now this is visible</p>
    <Children id={record.id};
  </div>
  );
}

// 2 - Parent - Right
render() {
  const { record } = this.state;
  const recordId = record ? record.id : null;

  return (
    <div>
      <p>Now this is visible</p>
      <Children id={recordId};
    </div>
  );
}

// Children
componentWillReceiveProps(nextProps) {
  console.log(nextProps.id);
}