访问 object 中的数组长度给我“TypeError：无法读取未定义的属性“长度”

Question

我收到一个错误TypeError: Cannot read property 'length' of undefined当试图访问我从 mapstatetoprops 获得的 object 中的数组长度时...成功返回 object。 in my component i call this.props.getuserdata in componentdidMount, and i mapstatetoprops currentUser state with getUserdata... although tt returns an object, it does not allow me to access the length of one of the properties arrays.... my mapstatetoprops写道：

当前用户：state.currentUser.getUserData

组件文件夹

    class Users extends Component {

  componentDidMount() {
    this.props.getUserData();
    this.props.getOtherUsers();
   }

  render() {
      console.log(this.props.currentUser.myStocks.length,'current user')
      
      return (
      <Container>
      
      </Container>
    )
  }
};
function mapStateToProps(state) {
  return {
   currentUser: state.currentUser.getUserData, 
    filteredUsers: state.filteredUsers.getOtherUsers,
    getUsersError: state.users.getUsersError
  };
}

export default compose(
  connect(mapStateToProps, { getUserData, getOtherUsers }),
  requireAuth
)(Users);

动作文件夹：

    export const getUserData = () => async (dispatch) => {
   try {
    const { data } = await axios.get('/api/user/profile', {
      headers: { authorization: localStorage.getItem('token') },
    });
    // console.log(data.myStocks[0],'inform')
    dispatch({ type: GET_USER_DATA, payload: data });
  } catch (e) {
    dispatch({
      type: GET_USER_DATA_ERROR,
      serverError: e,
      clientError: 'Something went wrong please refresh try again',
    });
  }
}

Answer 1

如果this.props.currentUser应该通过this.props.getUserData()获得，则问题可能是您的 API 调用未完成，而反应使用render方法。