How to access redux-store from within react's componentDIdMount()

问题

In the following code I am trying to pass the state.userData.userDetails from the redux-store to getleftpaneProductCatalogue(), but state.userData.userDetails is unaccessible to componentDidMount(). I tried assigning the state.userData.userDetails to this.prop.userProfile, but still this.prop.userProfile is an empty value. How to access the prop within componentDidMount?

import React,{Component} from 'react';
import { connect } from 'react-redux';
import {Row, Col } from 'react-materialize';
import {getleftpaneProductCatalogue} from '../actions/leftpane-actions';
import ProductCatalogueLeftPaneComp from '../components/pages/product-catalogue-leftpane';

class ProductCatalogueLeftPane extends Component {
    constructor(props) {
      super(props)

    }

    componentDidMount() {
      console.log('this.props^', JSON.stringify(this.props)); 
      this.props.getleftpaneProductCatalogue().then((data) => {
        console.log('productdata', data);
      })
    }

    render() {
      return (
        <div>
            {JSON.stringify(this.props.userProfile)}

       </div>
      )
    }

  }

  const mapStateToProps = (state) => {
    console.log('state^', JSON.stringify(state));
    return {leftpaneProductCatalogue: state.leftpaneProductCatalogue, userProfile: state.userData.userDetails};
  };

  const mapDispatchToProps = (dispatch) => {
    return {
      getleftpaneProductCatalogue: () => dispatch(getleftpaneProductCatalogue()),
    };
  };

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

回答1:

You can access the state directly in mapDispatchToProps and pass it to getleftpaneProductCatalogue:

componentDidMount() {
  const { dispatch, getleftpaneProductCatalogue }

  dispatch(getleftpaneProductCatalogue())   
}

const mapDispatchToProps = dispatch => {
  return {
    getleftpaneProductCatalogue: () => (dispatch, getState) => {
      const state = getState()
      const details = state.userData.userDetails

      return dispatch(getleftpaneProductCatalogue(details))
    },
    dispatch
  }
}

However, the way you're doing it, passing the state via mapStateToProps is still valid, but more verbose. Therefore the problem would be somewhere else.

Here's my bet. I guess you're getting the userData somewhere in your code with async API call and it's not being fetched yet. If that's the case - then you should wait for data being fetched firstly, then you can access it in your component ProductCatalogueLeftPane.

来源：https://stackoverflow.com/questions/51982033/how-to-access-redux-store-from-within-reacts-componentdidmount