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[英]React Native how to fetch Array data from Firebase Firestore?
[英]Resulting in a blank screen when listing data with Firebase(Firestore) in React Native
在 React Native 中使用 Firebase(Firestore) 列出数据的过程。
在我观看的视频中,他编写并运行了列出属于使用 firestore 的用户的硬币的代码。 即使我编写了相同的代码,它也不起作用。 是什么原因? 该代码没有给出错误,屏幕出现,但它没有列出。
问题是当我在控制台中列出它时它起作用了。 但是,当我尝试使用 FlatList 列出时,屏幕显示为空白。
import { View, Text, SafeAreaView, TouchableOpacity, FlatList } from 'react-native'
import React, { useContext, useState, useEffect } from 'react'
import IconFA5 from 'react-native-vector-icons/FontAwesome5'
import IconFA from 'react-native-vector-icons/FontAwesome'
import { deviceWidth, deviceHeight } from '../../utils/dimensions'
import { AuthContext } from '../../navigation/AuthProvider'
import { Formik, validateYupSchema } from 'formik'
import * as yup from 'yup'
import { firebase } from '@react-native-firebase/auth'
import auth from '@react-native-firebase/auth'
import firestore from '@react-native-firebase/firestore'
const color = '#aaa';
const HomeScreen = ({ navigation }) => {
const renderItem = (item) => {
<TouchableOpacity
key={item.id}
style={{
flexDirection: 'row',
width: '95%',
height: 60,
borderWidth: 1,
margin: 10,
borderRadius: 20,
padding: 10,
justifyContent: 'space-between',
alignItems: 'center'
}}>
<View style={{ flex: 1 }}>
<Text style={{
textAlign: 'left',
fontSize: 18
}}>{item.coinID}</Text>
</View>
<View style={{ flex: 1 }}>
<Text style={{
textAlign: 'right',
fontSize: 18
}}>{item.value}</Text>
</View>
</TouchableOpacity>
}
const { signOut, user } = useContext(AuthContext);
const [currentUser, setCurrentUser] = useState({});
const [userCoinList, setUserCoinList] = useState([]);
const usersColl = firestore().collection('users');
const coinsColl = firestore().collection('coins');
const userCoinsColl = firestore().collection('userCoins');
useEffect(() => {
return usersColl
.doc(user.uid)
.get()
.then(result => {
setCurrentUser(result.data());
userCoinsColl.onSnapshot((querySnapshot) => {
let list = [];
querySnapshot.forEach(doc => {
const { userID, coinID, value } = doc.data();
if (userID == user.uid) {
list.push({
id: doc.id,
userID,
coinID,
value
});
setUserCoinList(list);
}
});
});
});
}, []);
return (
<SafeAreaView style={{ width: '100%', height: '100%' }}>
<View style={{
width: '100%',
height: '90%',
padding: 5,
flex: 1,
alignItems: 'center'
}}>
<View>
<FlatList
style={{ flex: 3, backgroundColor: '#f00' }}
data={userCoinList}
keyExtractor={item => item.id}
renderItem={renderItem}
/>
{console.log(userCoinList)}
</View>
</View>
</SafeAreaView>
)
}
export default HomeScreen
您的renderItem
函数不返回任何内容。 这是一个修复。
const renderItem = (item) => {
return <TouchableOpacity
key={item.id}
style={{
flexDirection: 'row',
width: '95%',
height: 60,
borderWidth: 1,
margin: 10,
borderRadius: 20,
padding: 10,
justifyContent: 'space-between',
alignItems: 'center'
}}>
<View style={{ flex: 1 }}>
<Text style={{
textAlign: 'left',
fontSize: 18
}}>{item.coinID}</Text>
</View>
<View style={{ flex: 1 }}>
<Text style={{
textAlign: 'right',
fontSize: 18
}}>{item.value}</Text>
</View>
</TouchableOpacity>
}
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