如何在firebase数据库中查询反应？

Question

我在firebase中将以下数据结构作为实时数据库:

{
  "react" : {
    "url_01" : "https://stackoverflow.com/",
    "url_02" : "https://google.com/",
    "url_03" : "https://www.youtube.com/"
  }
}

我正在尝试查询React中的数据库以显示以下组件中的所有URL.

到目前为止,我得到它正确显示数据库中的第一个URL,但现在尝试将它们全部显示在div中<h1>.

class FirebaseDB extends React.Component {
  constructor() {
    super();
    this.state = {
      speed: [],
    };
  }

  componentDidMount() {
    const rootRef = firebase.database().ref().child('react');
    const speedRef = rootRef.child('url_01');
    speedRef.on('value', snap => {
      this.setState({
        speed: snap.val()
      });
    });
  }

  render() {
    return (

        <div>
          <h1>URL: {this.state.speed}</h1>
        </div>


    );
  }
}

Answer 1

componentDidMount() {
    const rootRef = firebase.database().ref();
    const speedRef = rootRef.child('react');

    speedRef.once("value", snap => {
        // Handle state
        let speedsUrls = []
        snap.forEach(child => {
            speedsUrls.push(child.val())
        });
        this.setState({speed: speedsUrls})
    });
}

render() {
    const SpeedURLS = this.state.speed.map(url => <h1>URL: {url}</h1>);
    return (
        <div>
            {SpeedURLS}
        </div>
    );
}