如何从 redux 存储中获取数据并在 React Native 的组件中使用它

Question

I set up Redux with react native. I manage to get the response from the backend in the action creator as res.data . But whenever I use it in my component it always evaluated to undefined or empty.

my action creator

export const getData = () => (dispatch: any) => {
  axios
    .get(`${API_URL}/api/request`)
    .then((res) => {
      dispatch({
        type: REQUESTS_FETCHED,
        requestData: res.data,
      });
      console.log(res.data);
    })
    .catch((err) => {
      console.error(err);
    });
};

And my reducer

const request = (state = initialState, action: any) => {
  switch (action.type) {
    case REQUESTS_FETCHED:
      return {
        ...state,
        requestData: action.requestData,
      };
    default:
      return state;
  }
};

The component as below

class Request extends Component {
  componentDidMount = () => {
    const {getData} = this.props;
    getData();
  };
  render() {
    const {requestData}: any = this.props;
    return (
      <View style={styles.container}>
        {requestData &&
          requestData.map((data: any) => {
              <Text>{data.value}</Text> 
          })}
      </View>
    );
  }
}

const mapStateToProps = (state: any) => ({
  requestData: state.request.requestdata,
});
const mapDispatchToProps = {
  getData,
};

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

NB this is the same code am using in reactjs. Thank you!

Answer 1

You need to return that text element. Just remove the curly brackets in your render method (arrow function will return the value directly this way), ie

  render() {
    const {requestData}: any = this.props;
    return (
      <View style={styles.container}>
        {requestData && requestData.map((data: any) => <Text>{data.value}</Text>)}
      </View>
    );
  }

Answer 2

You probably have typo in the mapStateToProps it should be state.request.requestData

Answer 3

The only thing I see is wrong is your mapStateToProps. Should be like this:

const mapStateToProps = (state: any) => ({
    requestData: state.requestdata,
});