以本机

Question

我正在尝试为本机列表视图编写一个过滤器。但它不起作用，我不知道为什么。 这是我的班级 -

＆＃13;

＆＃13;

import {
  AppRegistry,
  Image,
  ListView,
  StyleSheet,
  Text,
  TextInput,
  Navigator,
  TouchableHighlight,
  TouchableOpacity,
  filter,
  View
} from 'react-native';
var REQUEST_URL = GLOBAL.STATES_URL + '?apikey=' + GLOBAL.API_KEY;

class MainPage extends Component {
    
  constructor(props) {
    super(props);
    this.state = {
      dataSource: new ListView.DataSource({
        rowHasChanged: (row1, row2) => row1 !== row2,
      }),
      loaded: false,
      searchText: '',
      state: '',
    };
  }
  
  componentDidMount() {
    this.fetchData();
  }
  
  componentDidUpdate() {
    if (this.state.searchText === '') {
      this.fetchData();
    }
  }
  
  filterStates(searchText, states) {
    var text = searchText.toLowerCase();
    var rows = [];
   
   for (var i=0; i < states.length; i++) {
     var stateName = states[i].name.toLowerCase();
     if(stateName.search(text) !== -1){
         rows.push({
              name : states[i].name,
          });
     }
   }
       
    this.setState({
       dataSource: this.state.dataSource.cloneWithRows(rows),
       loaded : true,
     });
  }
  
  fetchData() {
    fetch(REQUEST_URL)
      .then((response) => response.json())
      .then((responseData) => {
        this.setState({
          dataSource: this.state.dataSource.cloneWithRows(responseData),
          loaded: true,
        });
      })
      .done();
  }
 
  setSearchText(event){
    var searchText = event.nativeEvent.text;
    this.setState({searchText});

    fetch(REQUEST_URL)
    .then((data) => {
          this.filterStates(searchText, data);    
    })
    .done();
 }
  
    
  render() {
    return (
      <Navigator
          renderScene={this.renderScene.bind(this)}
          navigator={this.props.navigator}
          navigationBar={
            <Navigator.NavigationBar style={{backgroundColor: '#246dd5'}}
                routeMapper={NavigationBarRouteMapper} />
          }
         />
    );
  }
  
  
  renderScene(route, navigator) {
    if (!this.state.loaded) {
      return this.renderLoadingView();
    }

    return (
      <View style={styles.combo}>
      
       <TextInput
         style={styles.searchBar}
         value={this.state.searchText}
         onChange={this.setSearchText.bind(this)}
         placeholder='Search' />   
      <ListView
        dataSource={this.state.dataSource}
        renderRow={this.renderState.bind(this)}
        // renderScrollComponent={props => <RecyclerViewBackedScrollView {...props} />}
        renderSeparator={(sectionID, rowID) => <View key={`${sectionID}-${rowID}`} style={styles.separator} />}
        style={styles.listView}
      />
      </View>
      
    );
  }
  
  renderLoadingView() {
    return (
      <View style={styles.container}>
        <Text>
          Loading States...
        </Text>
      </View>
    );
  }

  renderState(state,route,navigator) {
    return (
      <TouchableHighlight onPress={this.gotoPersonPage.bind(this,state)}>
         <View style={styles.row}> 
             <View style={styles.container}>
                   <Text style={styles.name}>{state.name}</Text>
             </View>
         </View>
      </TouchableHighlight>
   
    );
  }
  
  
  gotoPersonPage(state) {
    this.props.navigator.push({
      id: 'PersonPage',
      name: 'PersonPage',
      data: {name:state.name , abbreviation:state.abbreviation},
    });
  }
}

＆＃13;

＆＃13;

＆＃13;

任何人都可以告诉上述代码中的问题是什么，以及该问题的解决方案。 提前谢谢。

Answer 1

尝试在组件外部设置new ListView.DataSource({ rowHasChanged: (row1, row2) => row1 !== row2：

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

class MainPage extends Component {
  this.state = {
    dataSource: new ListView.DataSource({
      rowHasChanged: (row1, row2) => row1 !== row2,
    }),
    loaded: false,
    searchText: '',
    state: '',
  };
}

然后设置如下状态：

filterStates(searchText, states) {
    ...

    this.setState({
       dataSource: ds.cloneWithRows(rows),
       loaded : true,
     });
  }

和此：

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