javascript - 获取类型错误 :this. props.getMovieTree 不是函数

Question

我是 React Native 和 Redux 的新手，试图调用一个函数，但它给了我一个错误:

 this.prop.getMovieTree is undefined.

当我双击 getmovietree 时，它​​会将我重定向到正确的功能。但它在运行时出错并使我的应用程序崩溃。当我 console.log(this.props) 打印定义的值但是当我打印 console.log(this.props.getMovieTree()) 时打印未定义。

//在 App.js 中:

import {getMovieTree} from './src/actions/RestActions'
export class App extends Component {
  static propTypes = {
    getMovieTree: PropTypes.func,
  };
  constructor(props) {
    super(props)
   }
componentWillMount()
{
this.props.getMovieTree();//at this line getting error: getmovietree() is undefined

}
}
const mapStateToProps = state => {
  const { movieList } = state;

  return {movieList};
};
export default connect(mapStateToProps,getMovieTree )(App);

//在 RestAction.js 文件中:

import {MAGENTO_GET_MOVIE_TREE} from './types'
import {magento} from '../magento'
  export const getMovieTree = () => {
  return async dispatch => {
    try {
      const customer = await magento.getMovieTreeCall();
      dispatch({
        type: MAGENTO_GET_MOVIE_TREE,
        payload: customer
      });
    } catch (error) {
      console.log(error);
    }
  };
};

//在 Index.js 中:

export default magento => {
return{
    getMovieTreeCall : () => {
        return new Promise((resolve, reject) => {
         // const path = '/V1/AppVersion/';

          magento
            .send()
            .then(data => {
              resolve(data);

            })
            .catch(e => {
              console.log(e);
              reject(e);
            });
        });
      },
};


};



In magento/index.js:




class Magento {

    send(){

        fetch("https://api.themoviedb.org/3/movie/now_playing?api_key=55957fcf3ba81b137f8fc01ac5a31fb5&language=en-US")
        .then(response => response.json())
        .then((responseJson) => {
            return response.json()
            // this.setState({
            //     loading: false,
            //     dataSource: responseJson.results
            // })
        })
        .catch(error => console.log(error))
    }


}

export const magento = new Magento();

Answer 1

• 首先，在 Magento 类中，您应该使用 await 或 Promise 来处理异步任务。方法应该是这样的:

    async send(){            await fetch("https://api.themoviedb.org/3/movie/now_playing?api_key=55957fcf3ba81b137f8fc01ac5a31fb5&language=en-US")            .then(response => response.json())            .then((responseJson) => {                return response.json()                // this.setState({                //     loading: false,                //     dataSource: responseJson.results                // })            })            .catch(error => console.log(error))        }    }

• Then you should map dispatch to props and then connect it to component :

    const mapStateToProps = state => ({ getMovieTree: state.getMovieTree })
    //OR
    const mapDispatchToProps = dispatch => {
        return {
            getMovieTree: () => dispatch({  }) ///your desired action
        }
    }

    export default connect(mapStateToProps, mapDispatchToProps)(App); 

在这种情况下，我们不需要 mapDispatchToProps，您可以轻松地从 props 调用 getMovieTree。 connect() 的第二个参数是 mapDispatchProps 并且可以像这样取消定义。

export default connect(mapStateToProps)(App);