我在使用React Native和Firebase实时数据库时遇到了两个问题。
当我使用文本输入向列表中添加内容时,除了我刚刚添加的项目之外,所有列表项都会复制一次。只有刷新应用程序屏幕后才能解决这个问题。
当我从Firebase控制台或其他客户端删除某些内容时,列表不会实时更新。
import React, {useState, Component} from 'react';
import {
Text,
View,
Switch,
StyleSheet,
FlatList,
TextInput,
Button,
TouchableOpacity,
SafeAreaView,
VirtualizedList,
} from 'react-native';
import database from '@react-native-firebase/database';
class MenuBreakFastScreen extends React.Component {
state = {newItem: ''};
state = {itens: []};
componentDidMount() {
let dbRef = database().ref('/cafe/itens/');
this.listenerFirebase(dbRef);
}
listenerFirebase(dbRef) {
dbRef.on('value', dataSnapshot => {
const newItens = JSON.parse(JSON.stringify(this.state.itens));
dataSnapshot.forEach(child => {
newItens.push({
name: child.val().name,
key: child.key,
});
this.setState({itens:newItens});
});
});
}
addItem() {
if (this.state.newItem === '') {
return;
}
database().ref('/cafe/itens/').push({
name: this.state.newItem,
});
this.setState({
newItem: '',
});
}
render() {
const {itens} = this.state;
const {newItem} = this.state;
const renderItem = ( {item}) => {
return(
<ItemAsset title={item.name}/>
);
}
return (
<SafeAreaView
style={{flex: 1, justifyContent: 'center', alignItems: 'center'}}>
<FlatList
data={itens}
renderItem={renderItem}
keyExtractor={item => item.key}
/>
<SafeAreaView style={{flexDirection: 'row'}}>
<TextInput
style={styles.input}
onChangeText={text =>
this.setState({
newItem: text,
})
}
value={newItem}
/>
<TouchableOpacity style={styles.Botao} onPress={() => this.addItem()}>
<Text style={styles.BotaoTexto}>+</Text>
</TouchableOpacity>
</SafeAreaView>
</SafeAreaView>
);
}
}
const styles = StyleSheet.create({
texto: {
fontSize: 35,
},
input: {
color: '#000',
fontSize: 22,
borderWidth: 1,
flex: 8,
margin: 10,
},
BotaoTexto: {
color: '#fff',
fontSize: 22,
},
Botao: {
backgroundColor: '#000',
marginTop: 10,
padding: 10,
flex: 1,
alignItems: 'center',
margin: 10,
},
ListaContainer: {
flexDirection: 'row',
backgroundColor: '#000',
flex: 1,
},
item: {
backgroundColor: '#000',
padding: 20,
marginVertical: 8,
marginHorizontal: 16,
flexDirection: 'row',
},
title: {
color: '#ffff',
fontSize: 32,
},
});
const ItemAsset = ( {title} ) => {
return(
<View style={styles.item}>
<Text style={styles.title}>{title}</Text>
</View>
);
}
export default MenuBreakFastScreen;
state = { newItem: '' };
然后state = { itens: [] };
。 - Michael Rovinsky