Redux状态不更新数组

Question

I have an issue with my redux. This is the first time I am using it in React. I have managed to successfully use it for logging and registering users. However, I have an array of objects created on backend which I am fetching with axios. Axios logs the data and my action creator also logs data in payload. However, it does not update my new state. I have no idea what I'm doing wrong as I tried it exactly the same way as with my login and register states, however these were only boolean values. I have googled and searched for a solution. I tried mapping new array, Object.assign and many others but I can't seem to get it working. Is there any special way on creating new array in state? or can I just assign it action.payload? I appreciate all help

// 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 // I believe sth must be wrong here

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
  };
}

// component.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);

I am also including a link to an image with my redux logger.

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

There's probably a very small, stupid mistake in here as I'm quite new to React and completely new to Redux

Answer 1

You have a mistake, and I don't know if you a linter but in productsReducer.js you are importing constants from actions when it should be from 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;

So your reducer shouldn't be actually taken the proper case since it is undefined and It will so return the initial state.

Answer 2

I believe in mapStateToProps you're going to want to do the following:

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

To confirm productsList being passed through, can you add in a simple loop to the render function of component.js like below:

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

Answer 3

The way I do it with my reducer is

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

Try this way:

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));
  },
});