这个地方的react报错是什么原因呢

Question

百度了一会儿也没找到原因 --浏览器抛出的错误信息是Uncaught Error: Objects are not valid as a React child (found: object with keys {}). If you meant to render a collection of children, use an array instead or wrap the object using createFragment(object) from the React add-ons. Check the render method of App.

import React , { PureComponent,Component } from 'react'

import localStore from '../util/localStore.js'
import {cityName} from '../config/localStoreCity.js'
import  { connect } from 'react-redux'
import { bindActionCreators } from 'redux'
import * as actions from '../actions/action'

class App extends React.Component {
  constructor(props,context){
      super(props,context);
      this.state={
        inintdone:false
      }
  }
  render() {
    return(
      <div>
        <div  >{this.props.reducerCity}</div>
        {
          this.state.inintdone ?
          this.props.children
          :<span> 加载中1...</span>
        }
      </div>
    )
  }
  componentDidMount(){
    let name = localStore.getItem(cityName)
    if (name ==null){
        name='北京'
    }
    setTimeout(()=>{
      this.setState({
        inintdone :true
      })
    },1000)
    this.props.action.localCity({
            cityName: name,
    })
    
  }
}

function  mapStateToProps(state){
  console.log(state);
  return state
}
function mapDispatchToProps(dispatch) {
    return {
        action: bindActionCreators(actions, dispatch)
    }
}
export default connect(
    mapStateToProps,
    mapDispatchToProps
)(App)

我的想法是dispatch city以后 <div >{this.props.reducerCity}</div> 这里的城市会对应的变化，但是为什么金额会报错呢。而且我在mapStateToProps这里console了一下。为什么会执行了两遍。第一遍参数是空。第二遍就有了我的对应的参数。。

Answer 1

错误提示已经说了：
found: object with keys {}，你的render函数里写的是

<div  >{this.props.reducerCity}</div>

实际上看了你的代码应该是

<div  >{this.props.reducerCity.cityName}</div>

执行两边可能是因为你settimeout修改了state，会导致重新渲染页面

Answer 2

问题出在this.props.reducerCity。