React Native fetch() not working

Question

我正在尝试创建一个React Native应用程序，该应用程序从Google API获取数据，但遇到了一些问题（未处理的JS异常：未定义不是对象（正在评估"responseData[0].destination_addresss"）。

这是代码：

'use strict';
var React = require('react-native');
var {
  AppRegistry,
  StyleSheet,
  Text,
  View,
  TouchableHighlight,
} = React;
var INITIAL_DATA = [
  {city: 'CityName', duration: "0 hours"},
];
var REQUEST_URL = 'https://maps.googleapis.com/maps/api/distancematrix/json?mode=driving&language=en&origins=Austin&destinations=San+Francisco&key=PRIVACY';
var AwesomeProject = React.createClass({
  getInitialState: function() {
    return {
      data: INITIAL_DATA[0],
    };
  },
  componentDidMount: function() {
    this.fetchData();
  },
  fetchData: function() {
    fetch(REQUEST_URL)
      .then((response) => response.json())
      .then((responseData) => {
        this.setState({
          data: { city: responseData[0].destination_addresses[0].rendered, duration: responseData[0].rows[0].elements[0].duration.text.rendered },
        });  
      })
      .done();
  },
  render: function() {
    return (
      <View style={styles.container}>
        <View style={styles.textContainer}>
          <Text style={styles.city}>
            {this.state.data.city}
          </Text>
          <Text style={styles.text}>
            {this.state.data.duration}
          </Text>
        </View>
      </View>
    );
  }
});
var Dimensions = require('Dimensions');
var windowSize = Dimensions.get('window');
var styles = StyleSheet.create({
  container: {
    flex: 1,
    justifyContent: 'center',
    alignItems: 'center',
    backgroundColor: '#FFFFFF',
  },
  textContainer: {
    flex: 1,
    justifyContent: 'center',
    alignItems: 'center',
  },
  city: {
    fontSize: 30,
    textAlign: 'center',
    margin: 10,
  },
  text: {
    fontSize: 18,
    paddingLeft: 20,
    paddingRight: 20,
    textAlign: 'center',
    color: '#333333',
    marginBottom: 5,
  },
  buttonContainer: {
    bottom: 0,
    flex: .1,
    width: windowSize.width,
    backgroundColor: '#eee',
  },
  button: {
    flex: 1,
    alignItems: 'center',
    justifyContent: 'center',
  },
  buttonText: {
    fontSize: 30,
    color: '#666666',
  },
});

AppRegistry.registerComponent('AwesomeProject', () => AwesomeProject);

这就是我正在解析的json响应：

{
   "destination_addresses" : [ "San Francisco, CA, USA" ],
   "origin_addresses" : [ "Austin, TX, USA" ],
   "rows" : [
      {
         "elements" : [
            {
               "distance" : {
                  "text" : "2,830 km",
                  "value" : 2830409
               },
               "duration" : {
                  "text" : "1 day 1 hour",
                  "value" : 90952
               },
               "status" : "OK"
            }
         ]
      }
   ],
   "status" : "OK"
}

Answer 1

我认为您需要检查状态代码。

fetch(REQUEST_URL)
  .then((response) => response.json())
  .then((responseData) => {
    if(responseData.status === "OK"){
    this.setState({
      data: { city: responseData[0].destination_addresses[0].rendered,duration: responseData[0].rows[0].elements[0].duration.text.rendered },
    });  
    }else{
   // Do something
   }
  })
  .done();