当我尝试访问它时无法访问反应道具数据。 获取 TypeError 错误

Question

The Redux action creator get fired and makes fetch request to my server then returns data back to React Lead component. But I can access the the data to update the UI. When I console log the data it shows that is an array object, but when i try accessing the data in the component using map() it returns the leads props as undefined . Could it be because of the type checking I set for the incoming state?

Also, when I comment out the Type checking object set and try to access tha array object data I get a TypeError error: TypeError: props.leads is undefined , but I can console log it and it shows.

Why do I get an undefined data when I try to access it, but logs to the browser interpreter, when I only console log it?.

SOUCE CODE BELOW

Redux action:

import GET_LEADS from './types';

// GET LEADS
export const getLeads = () => (dispatch) => {
    fetch('/api/leads/')
    .then((response) => {
        if (response.status != 200) {
            throw new Error(response.statusText);
        }

        return response.json();
    })
    .then((res) => {
        dispatch({
            type: GET_LEADS,
            payload: res
        });
    })
    .catch((err) => {
        console.log(err)
    });
}

Redux reducers

Leads reducer:

import { GET_LEADS } from '../actions/types';

const initialState = {
    leads: []
};


export default function leads(state=initialState, action) {
    switch (action.types) {
        case GET_LEADS:
            return {
                ...state,
                leads: action.payload
            };
        default:
            return state;
    }
}

Combined reducer:

import { combineReducers } from 'redux';
import leads from './leads';

const rootReducer = combineReducers({
    leads: leads
});

export default rootReducer;

React Leads component (container, because it connect to redux):

import React, {useEffect} from 'react';

import {connect} from 'react-redux';
import { bindActionCreators } from 'redux';

import PropTypes from 'prop-types';

import { getLeads } from '../../actions/leads';

export function Lead(props) {

    useEffect(() => {
        props.getLeads();
    },[]);

    return (
        <React.Fragment>
            <div className="table-responsive-lg">
                <table className="table table-hover table-sm shadow-sm">
                    <thead>
                        <tr>
                            <th scope='col'>ID</th>
                            <th scope='col'>Title</th>
                            <th scope='col'>F-Name</th>
                            <th scope='col'>M-Name</th>
                            <th scope='col'>L-Name</th>
                            <th scope='col'>Phone</th>
                            <th scope='col'>Company</th>
                            <th scope='col'>Website</th>
                            <th scope='col'>Address</th>
                            <th scope='col'>Addr_1</th>
                            <th scope='col'>Addr_2</th>
                            <th scope='col'>Addr City</th>
                            <th scope='col'>Addr State</th>
                            <th scope='col'>Addr Country</th>
                            <th scope='col'>Sale Rep</th>
                            <th scope='col'>Status</th>
                            <th scope='col'>Priority</th>
                        </tr>
                    </thead>
                    <tbody>
                        {props.leads[0].map(lead => (   // <---- TypeError: props.leads is undefined
                            <tr key={lead.id}>
                                <td>{lead.id}</td>
                            </tr>
                        ))}
                        {console.log(props.leads)}
                    </tbody>
                </table>
            </div>
        </React.Fragment>
    );
}

Lead.propTypes = {
    leads: PropTypes.array.isRequired, // <--- type checking for array object
    getLeads: PropTypes.func.isRequired
};


const mapDispatchToProps = (dispatch) => bindActionCreators({getLeads}, dispatch);
const mapStateToProps = (state) => ({ leads: state.leads.leads });
export default connect(mapStateToProps, mapDispatchToProps)(Lead);

Answer 1

Try this:

In the tbody tag

{props.leads && props.leads[0].map(  
                            <tr key={lead.id}>
                                <td>{lead.id}</td>
                            </tr>
                        ))}

Answer 2

我认为你在 switch 语句中有错字它应该是switch(action.type)没有 's，这就是为什么当触发动作时它在减速器中找不到对应的动作类型并且数据没有加载到 redux 存储