Question

我需要从这个电影阵列的第一个位置获取String

仅在第一个位置上标题为“星球大战”

但我的代码却返回null

{
title: "The Basics - Networking",
description: "Your app fetched this from a remote endpoint!",
movies: [
{
title: "Star Wars",
releaseYear: "1977"
},
{
title: "Back to the Future",
releaseYear: "1985"
},
{
title: "The Matrix",
releaseYear: "1999"
},
{
title: "Inception",
releaseYear: "2010"
},
{
title: "Interstellar",
releaseYear: "2014"
}
]
}

constructor(props){
  super(props)
  this.state = {
    xName: '',
  };

}

componentDidMount() {
     fetch('https://facebook.github.io/react-native/movies.json')
        .then((response) => response.json())
        .then((responseJson) => 
        {this.setState({xName: responseJson.title[0]});})
        .catch((error) => {
            console.error(error);
        })

  alert(this.state.xName);
}

但是我的警报返回xName的null。它不能从标题设置状态

Answer 1

我会这样做

 class movieFetch extends Component{
        constructor(props){
            super(props);
            this.state = {movies: ''};
        }

    componentDidMount() {
         fetch('https://facebook.github.io/react-native/movies.json')
            .then((response) => response.json())
            .then((responseJson) => {this.setState({movies: responseJson.title});})
            .catch((error) => {
                console.error(error);
            })
    }

    render(){
        return (
          alert({this.state.movies[0].title}),
          <h3>{this.state.movies[0].title}</h3>
        );
    }

Answer 2

要获得星球大战冠军，您需要获得responseJson.movies[0].title而不是responseJson.title[0]

如何从API获取具有静态对象位置的String

2 个答案: