Question

在我的操作中，我从服务器接收到JSON响应，然后在reducer中设置了SET_CURRENT_STORAGE。在第二次调度中，我正在处理第一个操作的结果，并尝试使用名为getStorageCapacity()的自定义函数来设置有效负载。

以下是我的操作代码

export function fetchStorage() {
  return function(dispatch) {
    return fetch('/api/dashboard/storage', {
      method: 'POST',
      headers: { 'Content-Type': 'application/json' },
      credentials: 'include'
    })
      .then(response => response.json().then(body => ({ response, body })))
      .then(({ response, body }) => {
        //calculate storage
        if (!response.ok) {
        } else {
          var test1 = body.value;
          var take1 = Promise.resolve(
            dispatch({
              type: 'SET_CURRENT_STORAGE',
              payload: body.value
            })
          );
          take1.then(function() {
            dispatch({
              type: 'SET_CURRENT_STORAGE_CAPACITY',
              payload: getStorageCapacity(test1)
            });
          });
        }
      });
  };
}

export function getStorageLevel(payload) {
  return 'High';
}

export function getStorageCapacity(test1) {
  console.log('reached ' + test1);
  var arr = [];
  for (var key in test1) {
    console.log(test1[key]);
  }
  test1.forEach((item, i) => {
    console.log(item.capacity);
    return item.capacity;
  });
}

export function getStorageAvailable(payload) {
  return '150';
}

export function getStorageUsed(payload) {
  return '10';
}

下面是我的减速器代码

import {
  SET_CURRENT_STORAGE,
  SET_CURRENT_APPLICATION_SERVICES,
  SET_CURRENT_STORAGE_LEVEL,
  SET_CURRENT_STORAGE_CAPACITY,
  SET_CURRENT_STORAGE_AVAILABLE,
  SET_CURRENT_STORAGE_USED
} from '../actions/typesActions';
import isEmpty from '../validation/is-empty';
const initialState = {
  storageValue: [],
  storageLevel: 'Low',
  storageCapacity: '60',
  storageAvailable: '50',
  storageUsed: '10',
  appSerStatus: []
};

export default function(state = initialState, action) {
  console.log(state);

  switch (action.type) {
    case SET_CURRENT_STORAGE:
      return {
        ...state,
        storageValue: action.payload
      };
    case SET_CURRENT_APPLICATION_SERVICES:
      return {
        ...state,
        appSerStatus: action.payload
      };
    case SET_CURRENT_STORAGE_LEVEL:
      return {
        ...state,
        storageLevel: action.payload
      };
    case SET_CURRENT_STORAGE_CAPACITY:
      console.log(action);
      return {
        ...state,
        storageCapacity: action.payload
      };
    case SET_CURRENT_STORAGE_AVAILABLE:
      return {
        ...state,
        storageAvailable: action.payload
      };

    case SET_CURRENT_STORAGE_USED:
      return {
        ...state,
        storageUsed: action.payload
      };
    default:
      return state;
  }
}

每当我使用foreach进行处理时，它都会以 undefined 的形式返回，但是当我对getStorageCapacity()中的返回值进行硬编码时，该值将按预期返回。

你知道是什么原因吗？**

Answer 1

从forEach中返回并不会返回到函数getStorageCapacity，而是返回到循环之外。

也许您想尝试这样的事情：

export function getStorageCapacity(test1) {
  console.log('reached ' + test1);
  var arr = [];
  for (var key in test1) {
    console.log(test1[key]);
  }
  arr = test1.map((item, i) => {
    console.log(item.capacity);
    return item.capacity;
  });
  return arr;
}

Answer 2

return value from forEach is undefined

.forEach（）函数应该继续循环-它会忽略函数的返回值。

Redux反应不设置动作/减速器后的值

2 个答案: