如何在组件中接收先前发送到 redux 存储的值。 （始终未定义）

Question

Hi I am sending the value from a select to a redux Store:

import React, { Component } from 'react';
import { Select } from 'antd';
import { connect } from "react-redux";
import * as actions from '../store/actions/select';

class SelecionarCrypto extends Component {
  constructor(props) {
    super(props);

    this.onChange = this.onChange.bind(this);
    this.onBlur = this.onBlur.bind(this);
    this.onFocus = this.onFocus.bind(this);
    this.onSearch = this.onSearch.bind(this);

    console.log("(SelecionarCryto.js):",this.props);

    this.state = {
      ValorState: "nada"
    }


  };

 onChange(value) {
    console.log(`selected ${value}`);
    this.setState({ValorState: value});
    console.log("(SelecionarCryto.js)  New value onchange", this.state.ValorState)
    this.props.onSelectCrypto(value)

  }

  onBlur() {
    console.log('blur');
  }

  onFocus() {
    console.log('focus');
  }

  onSearch(val) {
    console.log('search:', val);
  }



render(){


const { Option } = Select;

console.log("(SelecionarCryto.js) New value Render: ", this.state.ValorState)








return (
  <Select
    showSearch
    style={{ width: 200 }}
    placeholder="Seleciona:"
    optionFilterProp="children"
    onChange={this.onChange}
    onFocus={this.onFocus}
    onBlur={this.onBlur}
    onSearch={this.onSearch}
    filterOption={(input, option) =>
      option.children.toLowerCase().indexOf(input.toLowerCase()) >= 0
    }
  >
    <Option value="ETH">ETH</Option>
    <Option value="BTC">BTC</Option>
    <Option value="XRP">XRP</Option>
  </Select>

  );
}


  }

  const mapStateToProps = state => {
    return {
      token: state.token,
      selectvalue: state.value

    };
  };

  //Dispaching to STORE:
const mapDispatchToProps = (dispatch) =>{
  return{
    onSelectCrypto: (value) => dispatch(actions.SelectCrypto(value))
  }
};

  export default connect(mapStateToProps, mapDispatchToProps)(SelecionarCrypto); 

Using the console I see how is working and the action is changin every time when I am using the select.

This parte ot the code i where I am conecting to the store to receive the props:

const mapStateToProps = state => {
  console.log("recibe mapStateToProps: ", state)
  return {
    token: state.token,
    ValorState: state.ValorState,
    username: state.username,
    selectvalue: state.value  // <<<---- This one 

  };
};

This is the props recived:

Why i always undefined? If my component is connected to the store when the value changes is not supposed to get the value?

Information about the reducer code: (parte os the code: )

const SelectCryptoValue = (state, action) => {  //  <--- This one.
    console.log("necesito esto:", state, " ", action)
    return updateObject(state, {
        selectvalue: action.value,
        error: null,
        loading: false

    });
}

const reducer = (state=initialState, action) => {
    switch (action.type) {
        case actionTypes.AUTH_START: return authStart(state, action);
        case actionTypes.AUTH_SUCCESS: return authSuccess(state, action);
        case actionTypes.AUTH_SUCCESS_USERNAME: return authSuccessUsername(state, action);
        case actionTypes.AUTH_FAIL: return authFail(state, action);
        case actionTypes.AUTH_LOGOUT: return authLogout(state, action);
        case actionTypes.SELECT_CRYPTO: return SelectCryptoValue(state, action);
        default:
            return state;
    }
}

export default reducer;

Answer 1

Without having any idea of how your reducer is implemented it's quite hard to say but I feel there is two possibilities:

• You are not defining properly the selectValue in your reducer
• You define it properly but using a mutation therefore not triggering a re-rendering of your react components