Javascript 实现pull以刷新平面列表
请帮我在我的应用程序上实现pull-to-refresh,我对react-native有点陌生,谢谢。我不知道如何处理刷新和刷新Javascript 实现pull以刷新平面列表,javascript,react-native,expo,Javascript,React Native,Expo,请帮我在我的应用程序上实现pull-to-refresh,我对react-native有点陌生,谢谢。我不知道如何处理刷新和刷新 class HomeScreen extends Component { state = { refreshing: false } _renderItem = ({ item }) => <ImageGrid item={item} /> _handleRefresh = () => { }; render() {
class HomeScreen extends Component {
state = { refreshing: false }
_renderItem = ({ item }) => <ImageGrid item={item} />
_handleRefresh = () => {
};
render() {
const { data } = this.props;
if (data.loading) {
return (
<Root>
<Loading size="large" />
</Root>
)
}
return (
<Root>
<HomeHeader />
<FlatList
contentContainerStyle={{ alignSelf: 'stretch' }}
data={data.getPosts}
keyExtractor={item => item._id}
renderItem={this._renderItem}
numColumns={3}
refreshing={this.state.refreshing}
onRefresh={this._handleRefresh}
/>
</Root>
);
}
}
export default graphql(GET_POSTS_QUERY)(HomeScreen);
类主屏幕扩展组件{
状态={刷新:错误}
_renderItem=({item})=>
_handleRefresh=()=>{
};
render(){
const{data}=this.props;
if(数据加载){
返回(
)
}
返回(
项目.\u id}
renderItem={this.\u renderItem}
numColumns={3}
刷新={this.state.refreshing}
onRefresh={this.\u handleRefresh}
/>
);
}
}
导出默认图形QL(获取帖子和查询)(主屏幕);
“拉入刷新”概念意味着列表可以手动刷新,因此可以在当前视图之外更改(例如从服务器获取)。因此,回调onRefresh
必须触发数据重新加载过程(例如,向服务器发送请求),并将refresh
变量设置为truthy值。这将通过显示加载指示器通知用户进程已启动。数据准备好后,您需要将刷新设置为falsy,以便视图将隐藏加载指示器。这是我能做的最好的事情
当我把它拉下来时,它不会从服务器上重新提取数据。我正在运行由Apollo连接到应用程序的graphql服务器,我不知道如何在_getData()函数中从服务器上获取数据 您还可以在
Flatlist
中使用refreshControl
,ScrollView
和任何其他列表组件
<FlatList
contentContainerStyle={{ alignSelf: 'stretch' }}
data={data.getPosts}
keyExtractor={(item) => item._id}
renderItem={this._renderItem}
numColumns={3}
refreshControl={
<RefreshControl
refreshing={this.state.refreshing}
onRefresh={this._handleRefresh}
/>
}
/>
item.\u id}
renderItem={this.\u renderItem}
numColumns={3}
刷新控制={
}
/>
设置变量
this.state = {
isFetching: false,
}
创建刷新功能
onRefresh() {
this.setState({isFetching: true,},() => {this.getApiData();});
}
在最后一组中,在平面列表中刷新和刷新
<FlatList
data={ this.state.FlatListItems }
onRefresh={() => this.onRefresh()}
refreshing={this.state.isFetching}
/>
//在flatlist中表示要刷新的pull的示例代码。相应地修改
import React, { Component } from 'react'
import { Text, View,StyleSheet,FlatList,Dimensions,Image,TouchableHighlight } from 'react-native'
export default class Home extends Component {
constructor(props)
{
super(props);
this.state = {
data : [],
gender : "",
isFetching: false,
}
}
componentWillMount()
{
this.searchRandomUser()
}
onRefresh() {
this.setState({ isFetching: true }, function() { this.searchRandomUser() });
}
searchRandomUser = async () =>
{
const RandomAPI = await fetch('https://randomuser.me/api/?results=20')
const APIValue = await RandomAPI.json();
const APIResults = APIValue.results
console.log(APIResults[0].email);
this.setState({
data:APIResults,
isFetching: false
})
}
render() {
return (
<View style = {styles.container}>
<TouchableHighlight
onPressOut = {this.searchRandomUser}
style = {{width:deviceWidth - 32, height:45,backgroundColor: 'green',justifyContent:"center",alignContent:"center"}}>
<Text style = {{fontSize:22,color: 'white',fontWeight: 'bold',textAlign:"center"}}>Reload Data</Text>
</TouchableHighlight>
<FlatList
data={this.state.data}
onRefresh={() => this.onRefresh()}
refreshing={this.state.isFetching}
keyExtractor = { (item, index) => index.toString() }
renderItem={({item}) =>
<View style = {styles.ContainerView}>
<View>
<Image
source={{uri : item.picture.large}}
style = {{height:100,width:100,borderRadius: 50,marginLeft: 4}}
resizeMode='contain'
/>
</View>
<View style = {{flexDirection: 'column',marginLeft:16,marginRight: 16,flexWrap:'wrap',alignSelf:"center",width: deviceWidth-160}}>
<Text>Email Id : {item.email}</Text>
<Text>Full Name : {this.state.gender} {item.name.first} {item.name.last}</Text>
<Text>Date of birth : {item.dob.age}</Text>
<Text>Phone number : {item.phone}</Text>
</View>
</View>
}
/>
</View>
)
}
}
const deviceWidth = Dimensions.get('window').width
const deviceHeight = Dimensions.get('window').height
const styles = StyleSheet.create({
container: {
flex: 1,
alignItems: 'center',
justifyContent: 'center',
marginTop:22
},
ContainerView:
{
// backgroundColor:'grey',
marginBottom:20,
paddingVertical:10,
backgroundColor: '#F5F5F5',
borderBottomWidth:0.5,
borderBottomColor:'grey',
width: deviceWidth-40,
marginLeft:20,
marginRight:20,
marginTop:20,
flexDirection:'row'
}
});
import React,{Component}来自“React”
从“react native”导入{文本、视图、样式表、平面列表、维度、图像、TouchableHighlight}
导出默认类Home extends组件{
建造师(道具)
{
超级(道具);
此.state={
数据:[],
性别:“,
isFetching:false,
}
}
组件willmount()
{
this.searchRandomUser()
}
onRefresh(){
this.setState({isFetching:true},function(){this.searchRandomUser()});
}
searchRandomUser=async()=>
{
const RandomAPI=等待取数('https://randomuser.me/api/?results=20')
const APIValue=wait RandomAPI.json();
const APIResults=APIValue.results
console.log(APIResults[0]。电子邮件);
这是我的国家({
数据:API结果,
isFetching:错误
})
}
render(){
返回(
重新加载数据
这是一个.onRefresh()}
刷新={this.state.isFetching}
keyExtractor={(项,索引)=>index.toString()}
renderItem={({item})=>
电子邮件Id:{item.Email}
全名:{this.state.gender}{item.Name.first}{item.Name.last}
出生日期:{item.dob.age}
电话号码:{item.Phone}
}
/>
)
}
}
const deviceWidth=Dimensions.get('window').width
const deviceHeight=维度.get('window').height
const styles=StyleSheet.create({
容器:{
弹性:1,
对齐项目:“居中”,
为内容辩护:“中心”,
玛金托普:22
},
ContainerView:
{
//背景颜色:'灰色',
marginBottom:20,
填充垂直:10,
背景颜色:'#f5',
边框底部宽度:0.5,
borderBottomColor:“灰色”,
宽度:设备宽度-40,
marginLeft:20,
marginRight:20,
玛金托普:20,
flexDirection:“行”
}
});
只需在滚动视图中使用即可,而不是在平面列表中使用“拉”刷新
设置刷新状态
this.state = {
isFetching: false,
}
在ScrollView中设置为onFresh
<ScrollView
refreshControl={
<RefreshControl
refreshing={this.state.refresh}
onRefresh={() => this.onRefresh()}
tintColor="red"
/>
}>
<FlatList data={data} renderItem={this._renderItem} numColumns={3} />
</ScrollView>;
如果在刷新时设置prop
onRefresh
,FlatList将自动设置RefreshControl
,尽管它是默认设置。嘿@Krish我这样做了,但数据中的最后一项不会消失,当我拉刷新“加载”时,它会卡住,无法获取新数据@DevAS在调用reload函数之前清空数组(当您设置state blank array flatlist must reload时),并检查您的flatlist是否仍显示最后一项。我不明白您的意思:/您说在调用onRefresh时清空数组?@DevAS我的意思是清空数组(在我的示例中为“FlatListItems”),它必须刷新平面列表,并且不应显示最后一项。请共享代码,以便我可以查看。上述代码的示例,Thanks@RishavKumar,Link=>如果您将代码片段粘贴到这里,将非常有用。
<ScrollView
refreshControl={
<RefreshControl
refreshing={this.state.refresh}
onRefresh={() => this.onRefresh()}
tintColor="red"
/>
}>
<FlatList data={data} renderItem={this._renderItem} numColumns={3} />
</ScrollView>;
onRefresh() {
this.setState({refresh: true});
setTimeout(() => {
this.setState({refresh: false});
}, 2000);
}
const [refreshing, setRefreshing] = useState(false)
<FlatList
style={{ padding: 15 }}
refreshControl={
<RefreshControl refreshing={refreshing}
onRefresh={_onRefresh}tintColor="#F8852D"/>
}
showsVerticalScrollIndicator={false}
data={listData}
renderItem={renderItem}
item={(item, index) => index.toStirng()}
onEndReachedThreshold={0.8}
onEndReached={() => onEndReached()}
ListFooterComponent={() => renderFooter()}
/>
const _onRefresh = () => {
console.log('_onRefresh')
setRefreshing(true);
getPosts();
};