当redux状态更改时，应该使用哪种React循环方法重新渲染组件？

Question

The React doc are unfortunately unclear for me at my level of understanding.

What cycle method should I use here instead of componentDidMount()? I want this component to update Google Map every time it gets new state from state.selectedShopInfo .

In my app user is clicking some list and every time he clicks this component gets new data.

I'm checking it with console.log(_.last(this.props.selectedShopInfo)); and it is working.

So what React cycle method should I use so every time { selectedShopInfo: state.selectedShopInfo } will change GoogleMap Component will change as well?

    import _ from 'lodash';
    import React, { Component } from 'react';
    import { connect } from 'react-redux';

    class GoogleMap extends Component {
      componentDidMount() {
        const lastSelectedShopInfo = _.last(this.props.selectedShopInfo);
        if (lastSelectedShopInfo !== undefined) {
          new google.maps.Map(this.refs.map, {
            zoom: 20,
            center: {
              lat: Number(lastSelectedShopInfo.latitude),
              lng: Number(lastSelectedShopInfo.longitude),
            },
          });
        }
      }

      render() {
        console.log(_.last(this.props.selectedShopInfo));
        return (
          <div>
            <hr />
            <div className="google-map" ref="map" />
            <hr />
          </div>
        );
      }
    }

    function mapStateToProps(state) {
      return { selectedShopInfo: state.selectedShopInfo };
    }

    export default connect(mapStateToProps)(GoogleMap);

Answer 1

Your component will re-render anytime a props or state change. This is the default behavior for React components.

So your component will re-render, but the logic you have in componentWillMount will not be applied more than once.

To solve this, move that logic to a separate function and call that both in componentDidMount() and in componentDidUpdate() . Something like this:

componentDidMount() {
  this.mapsInit();
}

componentDidUpdate(prevProps) {
  if (JSON.stringify(this.props) !== JSON.stringify(prevProps)) {
    this.mapsInit();
  }
}

mapsInit() {
  const lastSelectedShopInfo = _.last(this.props.selectedShopInfo);
    if (lastSelectedShopInfo !== undefined) {
      new google.maps.Map(this.refs.map, {
        zoom: 20,
        center: {
          lat: Number(lastSelectedShopInfo.latitude),
          lng: Number(lastSelectedShopInfo.longitude),
        },
      });
    }
  }
}

Answer 2

你应该首先呈现在地图中componentDidMount并更新地图componentWillReceiveProps 。