Javascript MapStateTrops对象未定义

我正在调用我的API，以使用其id获取特定对象

当我在

mapstatetops

方法中调用

console.log

时，会打印整个对象，但当我尝试使用

this.props.anuncio

访问它时，状态的“anuncio”属性未定义。我做错了什么

下面是我如何使用减速器和动作

import React from 'react'
import PropTypes from 'prop-types'
import { fetchAnuncio } from '../../actions/anuncios';
import { connect } from 'react-redux';
import Avatar from 'react-avatar';
import star from '../../imgs/star.png';

class AnuncioDetalhes extends React.Component {
  constructor(props) {
    super(props);
    this.state = {
      id: this.props.anuncio ? this.props.anuncio.id : null,
      img: this.props.anuncio ? this.props.anuncio.img : null
    }
  }


  componentDidMount() {
    if (this.props.match.params.id) {
      this.props.fetchAnuncio(this.props.match.params.id);
    }
  }

  render () {
    const {id, img} = this.state;
    return (
      <div>
      </div>

    );
  }
}

AnuncioDetalhes.propTypes = {
  fetchAnuncio: PropTypes.func.isRequired,
  history: PropTypes.object.isRequired
}

  function mapStateToProps(state, props) {

  if(props.match.params.id) {
    console.log(state.anuncios.find(item => item.id === 4))
    return {
      anuncio: state.anuncios.find(item => item.id === props.match.params.id)
    }
  }
  return { anuncio: null };
}

export default connect(mapStateToProps, {fetchAnuncio})(AnuncioDetalhes);

行动：

import { SET_ANUNCIOS, ANUNCIO_FETCHED } from '../actions/types';

export default function anuncios(state = [], action = {}) {
  switch(action.type) {

    case ANUNCIO_FETCHED:
      const index = state.findIndex(item => item.id === action.anuncio.id);

      if(index > -1) {
        return state.map(item => {
          if (item.id === action.anuncio.id) return action.anuncio;
          return item;
        });
      } else {
        return [
          ...state,
          action.anuncio
        ];
      }

    case SET_ANUNCIOS:
      return action.anuncios;
    default: return state;
  }
}

import axios from 'axios';
import Constants from '../components/Constants'
import { SET_ANUNCIOS, ANUNCIO_FETCHED } from './types';


export function setAnuncios(anuncios) {
  return {
    type: SET_ANUNCIOS,
    anuncios
  }
}

export function anuncioFetched(anuncio) {
  return {
    type: ANUNCIO_FETCHED,
    anuncio
  };
}

export function fetchAnuncios(cidade) {
  return dispatch => {
    return axios.get(Constants.BASE_URL + "anuncios/?user__cidade=" + cidade + "&status=2").then(res => {
      dispatch(setAnuncios(res.data.results));
    });
  }
}

export function fetchAnuncio(id) {
  return dispatch => {
    return axios.get(Constants.BASE_URL + "anuncios/" +`${id}`).then(res => {
      dispatch(anuncioFetched(res.data));
    });
  }
}

---

我认为您应该使用

componentWillReceiveProps

lifecycle方法来获取更新的道具

componentWillReceiveProps = (nextProps)  => {
    console.log(nextProps)
} 

---

this.state={id:props.anuncio？props.anuncio.id:null，img:props.anuncio？props.anuncio.img:null}

在您的构造函数中尝试类似的方法它不会记录一个字您是否将它添加到

AnuncioDetalhes

类中？更改

props.match.params.id

与

parseInt（props.match.params.id，10）