React Redux Uncaught TypeError：无法读取属性＆＃39; map＆＃39;未定义的

Question

我想与我现有的react-redux项目进行实时聊天。但是它给出了错误：     MessageList.js:16 Uncaught TypeError: Cannot read property 'map' of undefined     MessageList.js有两个组件：MessageForm.js 用于发送消息和消息列表的消息表单是列表组件

这是MessageList.js组件代码

import React from 'react';
import MessageForm from 'components/chat/MessageForm';
import { addMessage, deleteMessage } from 'actions/Chatactions';
import { connect } from 'react-redux';

const MessageList = ({messageList, dispatch}) => (

  <div>
    <h1>Mesajlar</h1>
    <MessageForm onChange={e => {
        if(e.keyCode == 13){
        dispatch(addMessage(e.target.value))
        e.target.value = ''
}
}}/>
{messageList.map((messageForm, index) => <p key={index}>{messageForm} <button onClick={e => {
    dispatch(deleteMessage(index))
}}>X</button></p>)}
</div>

)

function mapStateToProps(messageList) {
    return {
        messageList
        }
}



export default connect(mapStateToProps)(MessageList)
export default MessageList;

这里是这里是MessageForm.js组件代码

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

const MessageForm = ({onChange}) => (
  <div>
    <h3>New</h3>
    <input type="text" placeholder="Type your message here" onKeyUp={onChange}/>
  </div>
)

export default MessageForm

这是我的行动

export function addMessage(MessageForm){
    return {
        type: 'addMessage',
        MessageForm
        }
}

export function deleteMessage(index){
    return {
        type: 'deleteMessage',
        index
        }
}

这是我的reducer（MessageList.js）

import Immutable from 'immutable'

export default (state = Immutable.List(), action) => {
    switch(action.type) {
    case 'addMessage':
return state.unshift(action.MessageForm)
    case 'deleteMessage':
    return state.filter((MessageForm, index) => index !== action.index)
    default:
return state
}
}

这是我的商店（store.js与index.html的路径相同）

import { createStore } from 'redux';
import MessageList from './reducers/MessageList'
export default createStore(MessageList)