React：更改子组件后如何正确更新父组件的 state

Question

I'm new to React and was wondering if I could get some advice here.

I currently am using Mapbox and have map coordinates set to Manhattan along with a description about the city. I would like the descriptions and the location of the map to change every time a user presses a button (eg the map would move to Brooklyn upon the user clicking)

Essentially, I am trying to build this: https://docs.mapbox.com/mapbox-gl-js/example/playback-locations/ , but where the neighborhoods slide over only to button clicks. I wasn't sure how I could move this vanilla Javascript and html into React, so I tried to recreate the best I can.

My code is as follows. I'm aware that the child is a class component and the parent is a function component.

Parent Component

const locations = [
  {
    'id': '1',
    'title': 'Manhattan',
    'description': 'The capital of culture, finance, entertainment, and fashion. Need we say more?',
    'camera': {center: [-74.007, 40.7437], bearing: 25.3, zoom: 11.5}
  },
  {
    'id': '2',
    'title': 'Bronx',
    'description': "A fantastic zoo and botanical garden. Not to mention the birthplace of hip-hop!",
    'camera': {center: [-73.8709, 40.8255], bearing: 0, zoom: 12.21}
  },
  {
    'id': '3',
    'title': 'Brooklyn',
    'description': "This borough is experiencing a renaissance and continues to bring new surprises.",
    'camera': {center: [-73.9499, 40.626], bearing: -8.9, zoom: 11.68}
  },
  {
    'id': '4',
    'title': 'Queens',
    'description': "Experience one of the world's most diverse places!",
    'camera': {center: [-73.8432, 40.6923], bearing: 36, zoom: 11.37}
  },
  {
    'id': '5',
    'title': 'Staten Island',
    'description': 'A great place for family and friends with a stunning view, tons of parks, and a free ferry ride!',
    'camera': {center: [-74.1991, 40.5441], bearing: 28.4, zoom: 11.64}
  },
  {
    'title': 'Five Boroughs of New York',
    'description': 'New York City is made up of five boroughs: Bronx, Brooklyn, Manhattan, Queens and Staten Island. Each one has its own attractions-not to mention data!',
    'camera': {center: [-74.0315, 40.6989], zoom: 9.68, bearing: 0, pitch: 0}
  }
];


function Neighborhood() {
  const [count, setCount] = useState(0);
  const borough = <Boroughs data={locations[count]}/>
  const [map, setMap] = useState(borough); 

  function increase() {
    setCount(count+1);
    setMap(<Boroughs data={locations[count]}/>);
  }

  function decrease() {
    setCount(count-1);
    setMap(<Boroughs data={locations[count]}/>);
  }

  return (
    <div className="all-neighborhoods">
      <PageNavbar active="Listing" />
      <header className="App-header">
      </header>
      {count}
      <button onClick={decrease}>-</button>
      <button onClick={increase}>+</button>
      <div className="container-fluid">
        <div className="row d-flex flex-fill min-vh-100">
          {map}
        </div>
      </div>
    </div>
  );
}

export default Neighborhood; 

Child Component

mapboxgl.workerClass = MapboxWorker;
mapboxgl.accessToken = '<hidden>';
 
export default class Boroughs extends React.PureComponent {
  constructor(props) {
    super(props);
    this.state = {
      title: this.props.data.title,  
      description: this.props.data.description,
      lat: this.props.data.camera.center[0],
      long: this.props.data.camera.center[1],
      zoom: this.props.data.camera.zoom,
      bearing: this.props.data.camera.bearing
    }
    this.mapContainer = React.createRef();
  }

  componentDidMount() {
    const { lat, long, zoom, bearing } = this.state;
    const map = new mapboxgl.Map({
      container: this.mapContainer.current,
      style: 'mapbox://styles/mapbox/streets-v11',
      center: [parseFloat(lat), parseFloat(long)],
      maxZoom: 16,
      minZoom: 9,
      zoom: parseFloat(zoom),
      bearing: parseFloat(bearing),
      pitch: 50 
    });
  }

  render() {
    const { title, description } = this.state;
    return (
      <div ref={this.mapContainer} className="map-container flex-grow-1">
        <div className="map-overlay-container">
          <div className="map-overlay">
            <h2 id="location-title">{title}</h2>
            <p id="location-description">{description}</p>
          </div>
        </div>
      </div> 
    );
  }
}

Answer 1

Try reading up on the React Context API . Anything that is wrapped within the context provider will be exposed to the states of the context

Answer 2

It's not advisable for the child to change the state of the parent component. There is this hack though, Add a function in the parent that updates the state, pass it to the child as a prop and call it every time a change happens in the child component.