类型错误：未定义不是本机反应中的对象

Question

I am creating a podcast app using react native and PHP/MySQL.

I have stored each podcast and it's details in a MySQL database and am using PHP to get the information with a query.

I then fetch the information in react native and convert it to JSON format.

I am using react-native sound in order to play the podcast within the app.

Here is my code.

 constructor(props){
      super(props);
      this.FileUrlHolder = this.FileUrlHolder.bind(this);
      this.state = {
          playState:'paused', //playing, paused
          playSeconds:0,
          duration:0,
          FileUrlHolder: ''

      }

      this.sliderEditing = false;
  }

  componentDidMount(){
      fetch('http://da48c35f.ngrok.io/Filter.php', {
        method: 'POST',
        headers: {
          'Accept': 'application/json',
          'Content-Type': 'application/json',
        },
        body: JSON.stringify({

            // Getting the id.
            id: this.props.navigation.state.params.FlatListClickItemHolder
      })
    }).then((response) => response.json())
    .then((responseJson) => { 

        this.setState({ 
            FileUrlHolder: responseJson[0].FileUrl 
        }); 
        //console.log(responseJson[0].FileUrl);

    }).catch((error) => {
      console.error(error);
    })


  play = async () => {
      if(this.sound){
          this.sound.play(this.playComplete);
          this.setState({playState:'playing'});
      }else{

        const filepath = this.state.FileUrlHolder;
        console.log('[Play]', filepath);

          this.sound = new Sound(filepath, Sound.MAIN_BUNDLE, (error) => {
              if (error) {
                  console.log('failed to load the sound', error);
                  Alert.alert('Notice', 'audio file error. (Error code : 1)');
                  this.setState({playState:'paused'});
              }else{
                  this.setState({playState:'playing', duration:this.sound.getDuration()});
                  this.sound.play(this.playComplete);
              }
          });    
      }
  }

I am trying to access the state of the Fileurl within the play function so that I can use it to access the correct file to play.

When I run my app I get the following error.

TypeError: undefined is not an object (evaluating 'this.FileUrlHolder.bind')

How do I fix this?

Answer 1

FileUrlLoader 不是您的组件的属性，它是一个状态键，因此只需删除该绑定行

Answer 2

仅当您有名为 FileUrlHolder 的函数时才需要 this.FileUrlHolder = this.FileUrlHolder.bind(this)