Question

我正在使用FlatList加载一些记录。在FlatList上面我有一个按钮，当我点击这个按钮时，FlatList中加载了11230个项目，我想要的是使用onpress更新特定行背景颜色和flatlist项目的图像

   import React, { Component } from 'react';
   import {
     AppRegistry,
     StyleSheet,
     Text,
     View,
     FlatList,
     TouchableOpacity,
     TextInput,
     TouchableWithoutFeedback,
     Image 
   } from 'react-native'; // Impoert required components

   const GLOBAL_DATA = [];//To store json data
   const PER_PAGE = 10;
   const paginateArray = (array, pageSize, pageNumber) => {
     const _pageNumber = pageNumber - 1;
     return array.slice(_pageNumber * pageSize, (_pageNumber + 1) * pageSize);
   };

   for (let i = 0; i <= 100000; i++) {
     GLOBAL_DATA.push({
       key: i,
       produto: {
         descricao: 'Item number ' + i,
       }
     });
   }

   export default class flatlistdemo extends Component {
     constructor(props) {
       super(props);          
       this.state = {
         type: 'default',
         data: [],
         page: 1,
       };
     }

     componentDidMount() {
       this.setState({
         data: paginateArray(GLOBAL_DATA, PER_PAGE, this.state.page),
       });
     }

     getPagedOffers = () => {
       this.setState((state) => ({
         data: state.data.concat( paginateArray(GLOBAL_DATA, PER_PAGE, this.state.page) ),
       }));
     }

     handleLoadMore = () => {
       this.setState({
        page: this.state.page + 1,
       },
       () => {
         this.getPagedOffers();
        }
       );
     }

     render() {
       return (
         <View style={styles.container}>
           <FlatList
             data={this.state.data}
             onEndReached={this.handleLoadMore}
             onEndReachedThreshold={50}
             getItemLayout={(data, index) => (
               {length: 40, offset: 40 * index, index}
             )}
             renderItem={this._renderItem}
           />       
         </View>
       );
     }

     _renderItem = ({item}) => (
       <MyListItem
         produto={item.produto}
       />
     );
     }

     class MyListItem extends React.PureComponent {
       render() {
         return (
          <View 
            style={{
              paddingVertical: 10,
              backgroundColor:"#321AFE"
          }}>
            <TouchableOpacity onPress={() => this.updateRow(this.props.produto)}>
              <Text 
                style={{
                  color: '#000', 
                  height: 40,
                  justifyContent: 'center'
              }}>
                  {this.props.produto.descricao}
              </Text>
              <Image uri={{xyz}}
            </TouchableOpacity>
          </View>
         )
        }

       updateRow(item){
       //Here i want to update item of flatlist with new image and background color
       }
       }
       //Styles used for page
       const styles = StyleSheet.create({
          container: {
            marginTop: 30,
            alignItems: 'center',
          },
       });

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

如何使用映射功能更新flatlist行，以及如何使用导航导航到其他屏幕目前在导航方面面临问题无法读取未定义的属性“导航”

this.props.navigation.navigate("Home", UserID);

Answer 1

你可以使用flatlist的选定道具来实现这个目标（可能是）

你的构造函数应初始化所选

的空状态

constructor(props){
   super(props)
   this.state={
     slected:{}
   }
}

你的渲染功能应该如下所示

render(){
     <FlatList
              data={YOUR_DATA}
              removeClippedSubviews={false}
              keyExtractor={(item, index) => item.key}
              renderItem={this.renderItem.bind(this)}
              selected={this.state.selected} />
}

你的renderItem函数应该如下所示

renderItem= ({ item, index }) =>{
    let {selected } = this.state;
    let isSelected = !!selected[item.key]; // renderItem depends on state


    return (
     <View>
        {isSelected?
         <Text>Yes, I am Selected row</Text>:
         <Text>Please select me</Text>}
     </View>
    );
}

您更新所选

的功能

updateSelected =(isSingleSelected = false, rowsToUpdate = ARRAY OF ROWS NEED BE SELECTED)=>{
    if(isSingleSelected){
         let item = rowsToUpdate[0];
         this.setState((prevState)=>{
              let {prevSelected} = prevState;
              return {
                   selected:{[item.key]:!prevSelected[item.key]} //just toggle the state of current item
              }
         }
    }else{
       items = rowsToUpdate[0];
       this.setState((prevState)=>{
           let {prevSelected} = prevState;
           let objUpdating={}
           for(let i =0; i< items.length; i++){
               let item = items[i];
               objUpdating = {...objUpdating,[item.key]:!objUpdating[item.key]}        //using spread operator to avoid mutation you can try concat
           }
          return {
               selected:{...prevSelected, ...objUpdating} //matching keys will be overwritten
          }
       }
    }
}

试试这个并告诉我们这是否适合您

可以有更好的解决方案，请添加您的解决方案，因为我也在寻找更好的实施方案

在react-native中更新FlatList的特定行

1 个答案: