Redux 状态不更新数组

Question

我的 redux 有问题。这是我第一次在 React 中使用它。我已经成功地使用它来记录和注册用户。但是，我在后端创建了一组对象，我正在使用 axios 获取这些对象。 Axios 记录数据，我的动作创建者也在有效负载中记录数据。但是，它不会更新我的新状态。我不知道我做错了什么，因为我尝试了与登录和注册状态完全相同的方式，但是这些只是布尔值。我已经用谷歌搜索并搜索了解决方案。我尝试映射新数组、Object.assign 和许多其他数组，但似乎无法正常工作。在状态下创建新数组有什么特殊方法吗？或者我可以分配它 action.payload 吗？感谢所有帮助

// store.js

import { applyMiddleware, createStore } from 'redux';
import logger from 'redux-logger';
import thunk from 'redux-thunk';

import reducer from './reducers/reducer';

const middleware = applyMiddleware(logger, thunk);

export default createStore(reducer, middleware);

// rootReducer.js

import { combineReducers } from 'redux';

import registerReducer from './registerReducer';
import loginReducer from './loginReducer';
import productsReducer from './products';

export default combineReducers({
  registerReducer,
  loginReducer,
  productsReducer
});

// productsReducer // 我认为这里一定是错的

import { SHOW_PRODUCTS, SELECT_PRODUCT } from '../actions/products';

const initialState = {
  productsList: []
};

const productsReducer = (state = initialState, action) => {
  switch (action.type) {
    case SHOW_PRODUCTS: 
      return {...state, productsList: action.payload}
  }
  return state;
}

export default productsReducer;

//actions.js

import { SHOW_PRODUCTS, SELECT_PRODUCT } from './constants';

export function showProducts(products) {
  return {
    type: SHOW_PRODUCTS,
    payload: products
  };
}

// 组件.js

import React, { Component } from 'react';
import axios from 'axios';
import { connect } from 'react-redux';

import ProductsList from './ProductsList';
import { showProducts }  from '../actions/products';


class Home extends Component {
  constructor(props) {
    super(props);
  }

  componentWillMount() {
    this.props.getProducts(); 
  }

  render() {
    return(
      <div>Home Page
        <ProductsList />
      </div>
    )
  }
}

const mapStateToProps = (state) => {
  return {
    productsList: state.productsReducer.productsList
  };
}

const mapDispatchToProps = (dispatch) => {
  return {
    getProducts: () => {
      axios.get('http://localhost:5000/product/list')
      .then((res) => {
        console.log(res.data);
        dispatch(showProducts(res.data))
      })
      .catch(err => console.log(err))
    }
  }
}

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

我还在我的 redux 记录器中包含了一个图像链接。

https://i.stack.imgur.com/bTnYh.png

这里可能有一个非常小的、愚蠢的错误，因为我对 React 很陌生，对 Redux 完全陌生

Answer 1

你有一个错误，我不知道你是否是一个 linter，但在 productsReducer.js 中，你正在从 actions 导入 constants，而它应该来自 constants：

import { SHOW_PRODUCTS, SELECT_PRODUCT } from '../actions/constants'; // <- from constants instead

const initialState = {
  productsList: []
};

const productsReducer = (state = initialState, action) => {
  switch (action.type) {
    case SHOW_PRODUCTS: 
      return {...state, productsList: action.payload}
  }
  return state;
}

export default productsReducer;

所以你的reducer 实际上不应该被正确地使用case，因为它是undefined，它会返回初始状态。

Answer 2

我相信mapStateToProps 你会想要做以下事情：

const mapStateToProps = (state) => {
    return {
        productsList: state.productsList
    };
}

要确认 productsList 是否被传递，您能否在 component.js 的 render 函数中添加一个简单的循环，如下所示：

render() {
    const { productsList } = this.props;
    return(
        <div>
            Home Page
            {productsList.map((product, index) => (
                <div key={index}>{product.PROPERTY_NAME_HERE}</div>
            ))}
        </div>
    )
}

Answer 3

我使用减速器的方式是

import { SHOW_PRODUCTS, SELECT_PRODUCT } from '../actions/products';

const initialState = {
  productsList: []
};

const productsReducer = (state = initialState, action) => {
  switch (action.type) {
    case SHOW_PRODUCTS:
      let nextState = {...state};
      nextState.productsList = action.payload
      return nextState;
  }
  return state;
}

export default productsReducer;

Answer 4

试试这个方法：

componentWillMount() {
  this.getProducts(); 
}

getProducts() {
  axios.get('http://localhost:5000/product/list')
  .then((res) => {this.props.showProducts(res.data);})
  .catch(err => console.log(err));
}

const mapDispatchToProps = dispatch => ({
  showProducts: (data) => {
    dispatch(showProducts(data));
  },
});