react-native - React Native 评估'dataSource.rowIdentities

Question

我正在使用 React-Native 中的 dataSource 制作一个基本的 ListView，其中包含我获取的数据。

class Movies extends Component {
  render() {
    if (this.state.dataSource.getRowCount() === 0) {
      return (
        <View style={styles.container}>
          <Text>
            loading....
          </Text>
        </View>
      );
    }
    else {
      return (
        <View style={styles.container}>
          <ListView
            dataSource={this.state.dataSource}
            renderRow={this.renderRow.bind(this)}
          />
        </View>
      );
    }
  }

  constructor(props){
        super(props);
        this.state = {
          dataSource: new ListView.DataSource({
            rowHasChanged: (row1, row2) => row1 !== row2,
          }),
        };
  }

  componentWillMount() {
    this.fetchData();
  }

  fetchData(){
    fetch(HOT_MOVIES_URL)
      .then((response) => response.json())
      .then((responseData) => {
        if (responseData) {
          this.setState({
            dataSource: this.state.dataSource.cloneWithRows(responseData),
          });
        }
      })
      .done();
  }
}

然而，我得到了一个

undefined is not an object (evaluating 'dataSource.rowIdentities')

错误，尝试了很多方法也不起作用包含此 question ，有什么想法吗？

Answer 1

尝试将 ListView DataSource 设置为可重用变量，然后在需要时重用它。此外，您可能需要将 dataSource 设置为空数组，直到您的数据进来。尝试这样的事情:

var ds = new ListView.DataSource({ rowHasChanged: (row1, row2) => row1 !== row2 })

class Movies extends Component {
  render() {
    if (this.state.dataSource.getRowCount() === 0) {
      return (
        <View style={styles.container}>
          <Text>
            loading....
          </Text>
        </View>
      );
    }
    else {
      return (
        <View style={styles.container}>
          <ListView
            dataSource={this.state.dataSource}
            renderRow={this.renderRow.bind(this)}
          />
        </View>
      );
    }
  }
  constructor(props){
        super(props);
        this.state = {
          dataSource: ds.cloneWithRows([]),
        };
  }

  componentWillMount() {
    this.fetchData();
  }

  fetchData(){
    fetch(HOT_MOVIES_URL)
      .then((response) => response.json())
      .then((responseData) => {
        if (responseData) {
          this.setState({
            dataSource: ds.cloneWithRows(responseData),
          });
        }
      })
      .done();
  }
}