Reactjs无法将数据传递到父对象

// 父组件
class ParentComponent extends React.Component {
  constructor(props) {
    super(props);
    this.state = {
      dataFromChild: null
    };
  }

  handleDataFromChild = (data) => {
    this.setState({ dataFromChild: data });
  }

  render() {
    return (
      <div>
        <ChildComponent onData={this.handleDataFromChild} />
        <p>Data from child: {this.state.dataFromChild}</p>
      </div>
    );
  }
}

// 子组件
class ChildComponent extends React.Component {
  sendDataToParent = () => {
    const data = 'Hello from child';
    this.props.onData(data);
  }

  render() {
    return (
      <button onClick={this.sendDataToParent}>Send Data to Parent</button>
    );
  }
}