如何在react-redux中调度页面加载的操作？

Question

我必须显示包含大量数据的表格.有一个分页按钮,每页显示10条记录.我有一个名为"FETCH"的按钮点击它表填充.如何在页面加载时加载我的表.

action.js

import fetch from 'isomorphic-fetch';
export const ADD_BENEFICIARY = 'ADD_BENEFICIARY';
export const REMOVE_BENEFICIARY = 'REMOVE_BENEFICIARY';

export const ADD_PLAN_TO_COMPARE = 'ADD_PLAN_COMPARE';
export const REMOVE_PLAN_FROM_COMPARE = 'REMOVE_PLAN_COMPARE';
export const SHOW_PLAN_COMPARE = 'SHOW_PLAN_COMPARE';

export const NEXT_PAGE_PLAN_LIST = 'NEXT_PAGE_PLAN_LIST';
export const PREV_PAGE_PLAN_LIST = 'PREV_PAGE_PLAN_LIST';
export const REQUEST_PAGE_PLAN_LIST = 'REQUEST_PAGE_PLAN_LIST';
export const RECEIVE_PAGE_PLAN_LIST = 'RECEIVE_PAGE_PLAN_LIST';

export const showNextPageOfPlans = () => {

  return {
    type: NEXT_PAGE_PLAN_LIST
  }
}

export const showPreviousPageOfPlans = () => {

  return {
    type: PREV_PAGE_PLAN_LIST
  }
}

export const requestPageOfPlans = (startIdx, pageSize) => {

  return {
    type: REQUEST_PAGE_PLAN_LIST,
    start: startIdx,
    pageSize: pageSize
  }
}

export const receivePageOfPlans = (startIdx, json) => {

  return {
    type: RECEIVE_PAGE_PLAN_LIST,
    start: startIdx,
    plans: json
  }
}


export const fetchPlans = (startIdx, pageSize) => {

    var str = sessionStorage.getItem('formValue'); //JSON.stringify(formValues);

  return function (dispatch) {
    dispatch(requestPageOfPlans(startIdx, pageSize));
    return fetch('http://172.16.32.57:9090/alternatePlans/plans/list/', {method: 'post', body: str, headers: new Headers({'Content-Type': 'application/json'})  })
      .then(response => response.json())
      .then(json =>
        dispatch(receivePageOfPlans(startIdx, json))
      )
  }
}

reducer.js

import { REQUEST_PAGE_PLAN_LIST, RECEIVE_PAGE_PLAN_LIST,
         NEXT_PAGE_PLAN_LIST, PREV_PAGE_PLAN_LIST } from './actions';

const initialPaging = {

  startIndex: 0,
  lastIndex: 0,
  pageSize: 10
}

const paging = (state = initialCurrentPage, action) => {

  switch (action.type) {

    case NEXT_PAGE_PLAN_LIST:

      if (state.startIndex+state.pageSize <= state.lastIndex) {

        return { ...state, startIndex: state.startIndex+state.pageSize };
      }
      else {

        return state;
      }

    case PREV_PAGE_PLAN_LIST:

      if (state.startIndex-state.pageSize >= 0) {

        return { ...state, startIndex: state.startIndex-state.pageSize };
      }
      else {

        return state;
      }

    case REQUEST_PAGE_PLAN_LIST:

      return { ...state, isFetching: true };

    case RECEIVE_PAGE_PLAN_LIST:

      return { ...state, isFetching: false };

    default:
      return state;
  }

}

var initialPlans = [];

const plans = (state = initialPlans, action) => {

  switch (action.type) {

    case RECEIVE_PAGE_PLAN_LIST:
      return action.plans.plans;

    default:
      return state;
  }
}


const allReducers = (state = {}, action) => {

  let items = plans(state.plans, action);
  return {
    plans: items,
    paging: paging({ ...initialPaging, ...state.paging, lastIndex: items.length-1 }, action)
  }
}

export default allReducers;

PS我是react-redux的新手.官方文档很好,但解释却很少.

Answer 1

您可以从componentDidMount()页面的react组件或任何有意义的组件中调用它.所以在那个组件文件中:

import { requestPageOfPlans } from 'actions';
import React from 'react';
import { connect } from 'react-redux';

class MyComponent extends React.Component {
  componentDidMount() {
    this.props.requestPageOfPlans();
  }
}

export default connect((state) => state, { requestPageOfPlans })(MyComponent);

所以这里的关键是连接设置.第一个参数是您希望如何将状态(缩减器)转换为道具数据.根据需要进行调整.第二个是您希望绑定的操作.您也可以手动导入调度,但我个人喜欢这种模式.它将操作设置为组件上的道具,您可以这样调用它.只需根据需要将参数传递给它.这个页面:https://github.com/reactjs/react-redux/blob/master/docs/api.md#connectmapstatetoprops-mapdispatchtoprops-mergeprops-options更详细地解释了连接功能.

编辑

鉴于您在前端进行分页,您需要调整connect mapStateToProps函数以将分页数据传递给组件,然后循环遍历它以显示您需要的内容.我个人会在后端做分页,只是对每个页面做新的请求.取决于您期望拥有多少条记录.

所以在连接中做这样的事情:

export default connect((state) => {
  return {
    startIndex: state.paging.lastIndex,
    pageSize: state.paging.pageSize,
    lastIndex: state.paging.lastIndex,
    plans: state.plans
  };
}, { requestPageOfPlans })(MyComponent);

然后在您的组件中,使用这些索引遍历计划:

 render() {
   const plans = [];
   const maxIndex = Math.min(this.props.startIndex + this.props.pageSize, this.props.lastIndex);
   for (let i = this.props.startIndex || 0; i < maxIndex; i++) {
     const plan = this.props.plans[i];
     plans.push(<Plan key={plan.id} plan={plan} />);
   }

   return (
     <ul>{plans}</ul>
   );
 }

如果你有一个名为Plan的组件,那么再次对你计划如何渲染它做一些假设.但这大致是你如何使用它.