reducer.state.props 在嵌套动作 react/redux 中未定义 [英] reducer.state.props is undefined in nested actions react/redux

问题描述

新问题:根据更新的代码 - 当我在 reducer 中打印出有效负载时 - 我看到带有 api 数据的 maindata 但 SubData [{}, {}, {}] ..?

New issue: as per the updated code - when i print out payload in reducer - I see maindata with the api data but SubData [{}, {}, {}] ..?

更新代码:从 '../constants/types' 导入 { GET_DATA_AND_SUBDATA };

Updated code: import { GET_DATA_AND_SUBDATA } from '../constants/types';

export function getMainData() {
  return async function getMainData(dispatch) {
    const { data } = await getMainDataAPI();
    const subData = data.map((item) => {
      const endpoint = 'build with item.name';
      return Request.get(endpoint);
    });
     console.log('subddd' + subData);  prints -> **[object Promise],[object Promise],[object Promise]**
    dispatch({
      type: GET_DATA_AND_SUBDATA,
      payload: { data, subData }
    });
  };
}

async function getMainDataAPI() {
  const endpoint = 'url';
  return Request.get(endpoint);
}

推荐答案

问题在于您调度操作的方式.

The problem lies on the way you dispatch the actions.

您没有同时为 mainData 和 subdataOneData 提供数据.

You are not providing data for mainData and subdataOneData at the same time.

export function getData() {
    return async function getData(dispatch) {
        const { data } = await getDataAPI();

        // This will cause first re-render
        dispatch({ type: GET_DATA, payload: data }); 

        Object.keys(data).map((keyName, keyIndex) => {
            const endpoint = 'ENDPOINT';
            Request.get(endpoint).then((response) => {
                // This will cause second re-render
                dispatch({
                    type: GET_subdata + keyIndex,
                    payload: response.data });
                }); 

            return keyIndex;
        });
    };
}

首先渲染您的 subdataOneData 尚不可用.

At first render your subdataOneData is not availble yet.

您甚至没有在 reducer 中指定默认值，因此它将是 undefined.

You are not even specifying a default value in the reducer, therefore it will be undefined.

你可以像这样改变你的动作

You can change your action thunk like this

export function getData() {
    return async function getData(dispatch) {
        const { data } = await getDataAPI();

        const subDataResponse =  await Promise.all( 
            Object.keys(data).map( () => {
                const endpoint = 'ENDPOINT';
                return Request.get(endpoint)                    
            })
        )

        const subData = subDataResponse.map( response => response.data )

        dispatch({
            type: GET_DATA_AND_SUBDATA
            payload: { data, subData }
        });

    };
}

并相应地更改您的减速器，以便一次设置所有数据.

And change your reducer accordingly in order to set all data at once.

export default function myReducer(state = {}, action) {
    switch (action.type) {
        case GET_DATA_AND_SUBDATA:
        return {
            ...state,
            mainData: action.payload.data,
            subdataOneData: action.payload.subData[0],
            subdataTwoData: action.payload.subData[1]
        };        
        default:
            return state;
    }
}

注意:在 reducer 中设置初始状态也是一个好习惯.

Note: it's also a good practice to set your initial state in the reducer.

const initialState = {
    mainData: // SET YOUR INITIAL DATA
    subdataOneData: // SET YOUR INITIAL DATA
    subdataTwoData: // SET YOUR INITIAL DATA
}

export default function myReducer(initialState, action) {

这篇关于reducer.state.props 在嵌套动作 react/redux 中未定义的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！