React -我无法使用data.json()填充我的下拉列表

constructor(props) {
  super(props);
  this.state = {
    dropdownData: []
  };
}

componentDidMount() {
  fetch('your_api_endpoint')
    .then(response => response.json())
    .then(data => {
      this.setState({ dropdownData: data });
    })
    .catch(error => {
      console.error('Error fetching dropdown data:', error);
    });
}

render() {
  const { dropdownData } = this.state;

  return (
    <select>
      {dropdownData.map(item => (
        <option key={item.id} value={item.value}>{item.label}</option>
      ))}
    </select>
  );
}